Systems and methods for volumetric acquisition in a single-sided mri scanner

ABSTRACT

A method for performing magnetic resonance imaging is provided. The method includes providing a magnetic resonance imaging system comprising: a radio frequency receive system comprising a radio frequency receive coil, and a housing, wherein the housing comprises a permanent magnet for providing an inhomogeneous permanent gradient field, a radio frequency transmit system, and a single-sided gradient coil set. The method also includes placing the receive coil proximate a target subject; applying a sequence of chirped pulses via the transmit system; applying a multi-slice excitation along the inhomogeneous permanent gradient field; applying a plurality of gradient pulses via the gradient coil set orthogonal to the inhomogeneous permanent gradient field; acquiring a signal of the target subject via the receive system, wherein the signal comprises at least two chirped pulses; and forming a magnetic resonance image of the target subject.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application claiming priorityunder 35 U.S.C. § 120 to U.S. patent application Ser. No. 17/438,898,entitled “SYSTEMS AND METHODS FOR VOLUMETRIC ACQUISITION IN ASINGLE-SIDED MRI SCANNER,” filed Sep. 13, 2021, which is a U.S. NationalStage Entry under 35 U.S.C. § 371 of International PCT Application No.PCT/US2020/024778, entitled “SYSTEMS AND METHODS FOR VOLUMETRICACQUISITION IN A SINGLE-SIDED MRI SYSTEM,” filed Mar. 25, 2020, whichclaims the benefit of priority under 35 U.S.C. § 119(e) to U.S.Provisional Application No. 62/823,511, entitled “SYSTEMS AND METHODSFOR VOLUMETRIC ACQUISITION IN A SINGLE-SIDED MRI SYSTEM”, filed on Mar.25, 2019, which are each incorporated by reference herein in theirrespective entireties.

BACKGROUND

The embodiments disclosed herein are generally directed towards systemsand methods for effectively collecting nuclear magnetic resonancespectra and magnetic resonance images in inhomogeneous fields.

Several methods exist for collecting nuclear magnetic resonance (NMR)spectra and magnetic resonance (MR) images in inhomogeneous fields.Typically, the inhomogeneity of the field is a nuisance to be avoided.Rarely is the inhomogeneous field a source of spatial information.Relevant methods for imaging in inhomogeneous fields include use of widebandwidth pulses and multi-slice excitation. Both however deal with thechallenge of imaging in an inhomogeneous permanent field. Therefore,there is a need for improved methods using wide bandwidth pulses andmulti-slice excitation for collecting NMR spectra and MR images ininhomogeneous fields.

SUMMARY

In accordance with various embodiments, a method for performing magneticresonance imaging is provided. The method includes providing a magneticresonance imaging system comprising a radio frequency receive systemcomprising a radio frequency receive coil, and a housing, wherein thehousing comprises a permanent magnet for providing an inhomogeneouspermanent gradient field, a radio frequency transmit system, and asingle-sided gradient coil set. The method further comprises placing thereceive coil proximate a target subject; applying a sequence of chirpedpulses via the transmit system; applying a multi-slice excitation alongthe inhomogeneous permanent gradient field; applying a plurality ofgradient pulses via the gradient coil set orthogonal to theinhomogeneous permanent gradient field; acquiring a signal of the targetsubject via the receive system, wherein the signal comprises at leasttwo chirped pulses; and forming a magnetic resonance image of the targetsubject.

In accordance with various embodiments, a method for performing magneticresonance imaging is provided. The method includes providing an imagingsystem comprising a radio frequency receive coil, and a permanent magnetfor providing a permanent gradient field. The method further comprisesplacing the receive coil proximate a target subject; applying a sequenceof chirped pulses having a wide bandwidth; applying a multi-sliceexcitation along the permanent gradient field, wherein the multi-sliceexcitation includes exciting multiple slices along an axis of thepermanent gradient field, wherein each of the multiple slices has abandwidth that is similar to the wide bandwidth of the chirped pulses;applying a phase encoding field along two orthogonal directionsperpendicular to the axis of the permanent gradient field; and acquiringa magnetic resonance image of the target subject.

In accordance with various embodiments, a method for performing magneticresonance imaging is provided. The method includes providing a permanentgradient magnetic field; placing a receive coil proximate a targetsubject; applying a sequence of chirped pulses having a wide bandwidth;selecting a slice selection gradient having the same wide bandwidth;applying a multi-slice excitation technique along an axis of thepermanent gradient magnetic field; applying a plurality of gradientpulses orthogonal to the permanent gradient magnetic field; acquiring asignal of the target subject via the receive coil; and forming amagnetic resonance image of the target subject.

In accordance with various embodiments, a magnetic resonance imagingsystem is provided. The system includes a radio frequency receive systemcomprising a radio frequency receive coil configured to be placedproximate a target subject. The receive system is configured to delivera signal of a target subject for forming a magnetic resonance image ofthe target subject, wherein the signal comprises at least two chirpedpulses. The system includes a housing, wherein the housing comprises apermanent magnet for providing an inhomogeneous permanent gradientfield. The imaging system is configured to apply a multi-sliceexcitation along the inhomogeneous permanent gradient field, a radiofrequency transmit system configured to deliver a sequence of chirpedpulses, and a single-sided gradient coil set configured to deliver aplurality of gradient pulses orthogonal to the inhomogeneous permanentgradient field.

In accordance with various embodiments, a non-transitorycomputer-readable medium in which a program is stored for causing acomputer to perform a method for performing magnetic resonance imagingis provided. The method includes providing a magnetic resonance imagingsystem. The system includes a radio frequency receive system comprisinga radio frequency receive coil, and a housing. The housing includes apermanent magnet for providing an inhomogeneous permanent gradientfield, a radio frequency transmit system, and a single-sided gradientcoil set. The method further includes placing the receive coil proximatea target subject; applying a sequence of chirped pulses via the transmitsystem; applying a multi-slice excitation along the inhomogeneouspermanent gradient field; applying a plurality of gradient pulses viathe gradient coil set orthogonal to the inhomogeneous permanent gradientfield; acquiring a signal of the target subject via the receive system,wherein the signal comprises at least two chirped pulses; and forming amagnetic resonance image of the target subject.

In accordance with various embodiments, a non-transitorycomputer-readable medium in which a program is stored for causing acomputer to perform a method for performing magnetic resonance imagingis provided. The method includes providing an imaging system comprisinga radio frequency receive coil, and a permanent magnet for providing apermanent gradient field. The method further includes placing thereceive coil proximate a target subject; applying a sequence of chirpedpulses having a wide bandwidth; applying a multi-slice excitation alongthe permanent gradient field, wherein the multi-slice excitationincludes exciting multiple slices along an axis of the permanentgradient field, wherein each of the multiple slices has a bandwidth thatis similar to the wide bandwidth of the chirped pulses; applying a phaseencoding field along two orthogonal directions perpendicular to the axisof the permanent gradient field; and acquiring a magnetic resonanceimage of the target subject.

In accordance with various embodiments, a non-transitorycomputer-readable medium in which a program is stored for causing acomputer to perform a method for performing magnetic resonance imagingis provided. The method includes providing a permanent gradient magneticfield; placing a receive coil proximate a target subject; applying asequence of chirped pulses having a wide bandwidth; selecting a sliceselection gradient having the same wide bandwidth; applying amulti-slice excitation technique along an axis of the permanent gradientmagnetic field; applying a plurality of gradient pulses orthogonal tothe permanent gradient magnetic field; acquiring a signal of the targetsubject via the receive coil; and forming a magnetic resonance image ofthe target subject.

These and other aspects and implementations are discussed in detailbelow. The foregoing information and the following detailed descriptioninclude illustrative examples of various aspects and implementations,and provide an overview or framework for understanding the nature andcharacter of the claimed aspects and implementations. The drawingsprovide illustration and a further understanding of the various aspectsand implementations, and are incorporated in and constitute a part ofthis specification.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not intended to be drawn to scale. Likereference numbers and designations in the various drawings indicate likeelements. For purposes of clarity, not every component may be labeled inevery drawing. In the drawings:

FIG. 1 is a schematic illustration of a magnetic resonance imagingsystem, in accordance with various embodiments.

FIG. 2A is a schematic illustration of a magnetic resonance imagingsystem, in accordance with various embodiments.

FIG. 2B illustrates an exploded view of the magnetic resonance imagingsystem shown in FIG. 2A.

FIG. 2C is a schematic front view of the magnetic resonance imagingsystem shown in FIG. 2A, in accordance with various embodiments.

FIG. 2D is a schematic side view of the magnetic resonance imagingsystem shown in FIG. 2A, in accordance with various embodiments.

FIG. 3 is a schematic view of an implementation of a magnetic imagingapparatus, according to various embodiments.

FIG. 4 is a schematic view of an implementation of a magnetic imagingapparatus, according to various embodiments.

FIG. 5 is a schematic front view of a magnetic resonance imaging system500, according to various embodiments.

FIG. 6A is an example schematic illustration of a radio frequencyreceive coil (RF-RX) array including individual coil elements, inaccordance with various embodiments.

FIG. 6B is an example illustration of a loop coil along with examplecalculations for a loop coil magnetic field, in accordance with variousembodiments.

FIG. 6C is an example X-Y chart illustrating the magnetic field as afunction of radius of a loop coil, in accordance with variousembodiments disclosed herein.

FIG. 6D is a cross-sectional illustration of a portion of the humanbody, namely in the area of the prostate.

FIG. 7A is an example schematic pulse sequence diagram for atwo-dimensional pulse sequence, in accordance with various embodiments.

FIG. 7B is an example schematic pulse sequence diagram for athree-dimensional pulse sequence, in accordance with variousembodiments.

FIG. 8 is a schematic pulse sequence diagram for a system with chirpedpulses and a permanent slice selection gradient, in accordance withvarious embodiments.

FIG. 9 illustrates example pulse sequences, in accordance with variousembodiments.

FIG. 10 illustrates an example position of patient for imaging in amagnetic resonance imaging system, according to various embodiments.

FIG. 11 is a schematic illustration of an example magnetic resonanceimaging system, in accordance with various embodiments.

FIG. 12 is a schematic illustration of an example magnetic resonanceimaging system, in accordance with various embodiments.

FIG. 13 is a schematic illustration of an example magnetic resonanceimaging system, in accordance with various embodiments.

FIG. 14 is a schematic illustration of an example magnetic resonanceimaging system, in accordance with various embodiments.

FIG. 15 is a flowchart for a method for performing magnetic resonanceimaging, according to various embodiments.

FIG. 16 is a flowchart for another method for performing magneticresonance imaging, according to various embodiments.

FIG. 17 is a flowchart for another method for performing magneticresonance imaging, according to various embodiments.

FIG. 18 is a block diagram that illustrates a computer system, inaccordance with various embodiments.

It is to be understood that the figures are not necessarily drawn toscale, nor are the objects in the figures necessarily drawn to scale inrelationship to one another. The figures are depictions that areintended to bring clarity and understanding to various embodiments ofapparatuses, systems, and methods disclosed herein. Wherever possible,the same reference numbers will be used throughout the drawings to referto the same or like parts. Moreover, it should be appreciated that thedrawings are not intended to limit the scope of the present teachings inany way.

DETAILED DESCRIPTION

The following description of various embodiments is exemplary andexplanatory only and is not to be construed as limiting or restrictivein any way. Other embodiments, features, objects, and advantages of thepresent teachings will be apparent from the description and accompanyingdrawings, and from the claims.

It should be understood that any use of subheadings herein are fororganizational purposes, and should not be read to limit the applicationof those subheaded features to the various embodiments herein. Each andevery feature described herein is applicable and usable in all thevarious embodiments discussed herein and that all features describedherein can be used in any contemplated combination, regardless of thespecific example embodiments that are described herein. It shouldfurther be noted that exemplary description of specific features areused, largely for informational purposes, and not in any way to limitthe design, subfeature, and functionality of the specifically describedfeature.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs.

All publications mentioned herein are incorporated herein by referencefor the purpose of describing and disclosing devices, compositions,formulations and methodologies which are described in the publicationand which might be used in connection with the present disclosure.

As used herein, the terms “comprise”, “comprises”, “comprising”,“contain”, “contains”, “containing”, “have”, “having” “include”,“includes”, and “including” and their variants are not intended to belimiting, are inclusive or open-ended and do not exclude additional,unrecited additives, components, integers, elements or method steps. Forexample, a process, method, system, composition, kit, or apparatus thatcomprises a list of features is not necessarily limited only to thosefeatures but may include other features not expressly listed or inherentto such process, method, system, composition, kit, or apparatus.

As discussed herein, and in accordance with various embodiments, thevarious systems, and various combinations of features that make up thevarious system embodiments, can include a magnetic resonance imagingsystem. In accordance with various embodiments, the magnetic resonanceimaging system is a single-sided magnetic resonance imaging system thatcomprises a magnetic resonance imaging scanner or a magnetic resonanceimaging spectrometer. In accordance with various embodiments, themagnetic resonance imaging system can include a magnet assembly forproviding a magnetic field required for imaging an anatomical portion ofa patient. In accordance with various embodiments, the magneticresonance imaging system can be configured for imaging in a region ofinterest which resides outside of the magnet assembly.

Typical magnet resonant assemblies used in modern magnetic resonanceimaging systems include, for example, a birdcage coil configuration. Atypical birdcage configuration includes, for example, a radio frequencytransmission (transmit) coil that can include two large rings placed onopposite sides of the imaging region (i.e., the region of interest wherethe patient resides) that are each electrically connected by one or morerungs. Since the imaging signal improves the more the coil surrounds thepatient, the birdcage coil is typically configured to encompass apatient so that the signal produced from within the imaging region,i.e., the region of interest where the anatomical target portion of thepatient resides, is sufficiently uniform. To improve patient comfort andreduce burdensome movement limitations of the current magnetic resonanceimaging systems, the disclosure as described herein generally relates toa magnetic resonance imaging system that includes a single-sidedmagnetic resonance imaging system and its applications.

As described herein, the disclosed single-sided magnetic resonanceimaging system can be configured to image the patient from one sidewhile providing access to the patient from both sides. This is possibledue to the single-sided magnetic resonance imaging system that containsan access aperture (also referred to herein as “aperture”, “hole” or“bore”), which is configured to project magnetic fields in the region ofinterest which resides completely outside of the magnet assembly and themagnetic resonance imaging system. Since not being completely surroundedby the electromagnetic field producing materials and imaging systemcomponents as in current state of the art systems, the novelsingle-sided configuration as described herein offer less restriction inpatient movement while reducing unnecessary burden during situatingand/or removing of the patient from the magnetic resonance imagingsystem. In accordance with various embodiments as described herein, thepatient would not feel entrapped in the disclosed magnetic resonanceimaging system with the placement of the magnet assembly on the side ofthe patient during imaging. The configuration that enables single-sidedor imaging from a side is made possible by the disclosed systemcomponents as discussed herein.

System Embodiments

In accordance with various embodiments, the various systems, and variouscombinations of features that make up the various system components andembodiments of the disclosed magnetic resonance imaging system aredisclosed herein.

In accordance with various embodiments, a magnetic resonance imagingsystem is disclosed herein. In accordance with various embodiments, thesystem includes a housing having a front surface, a permanent magnet forproviding a static magnetic field, an access aperture (also referred toherein as “aperture”, “hole” or “bore”) within the permanent magnetassembly, a radio frequency transmit coil, and a single-sided gradientcoil set. In accordance with various embodiments, the radio frequencytransmit coil and the single-sided gradient coil set are positionedproximate to the front surface. In accordance with various embodiments,the system includes an electromagnet, a radio frequency receive coil,and a power source. In accordance with various embodiments, the powersource is configured to flow current through at least one of the radiofrequency transmit coil, the single-sided gradient coil set, or theelectromagnet to generate an electromagnetic field in a region ofinterest. In accordance with various embodiments, the region of interestresides outside the front surface.

In accordance with various embodiments, the radio frequency transmitcoil and the single-sided gradient coil set are located on the frontsurface. In accordance with various embodiments, the front surface is aconcave surface. In accordance with various embodiments, the permanentmagnet has an aperture through center of the permanent magnet. Inaccordance with various embodiments, the static magnetic field of thepermanent magnet ranges from 1 mT to 1 T. In accordance with variousembodiments, the static magnetic field of the permanent magnet rangesfrom 10 mT to 195 mT.

In accordance with various embodiments, the radio frequency transmitcoil includes a first ring and a second ring that are connected via oneor more capacitors and/or one or more rungs. In accordance with variousembodiments, the radio frequency transmit coil is non-planar andoriented to partially surround the region of interest. In accordancewith various embodiments, the single-sided gradient coil set isnon-planar and oriented to partially surround the region of interest. Inaccordance with various embodiments, the single-sided gradient coil setis configured to project a magnetic field gradient to the region ofinterest. In accordance with various embodiments, the single-sidedgradient coil set includes one or more first spiral coils at a firstposition and one or more second spiral coils at a second position, thefirst position and the second position being located opposite each otherabout a center region of the single-sided gradient coil set. Inaccordance with various embodiments, the single-sided gradient coil sethas a rise time less than 10 μs.

In accordance with various embodiments, the electromagnet is configuredto alter the static magnetic field of the permanent magnet within theregion of interest. In accordance with various embodiments, theelectromagnet has a magnetic field strength from 10 mT to 1 T. Inaccordance with various embodiments, the radio frequency receive coil isa flexible coil configured to be affixed to an anatomical portion of apatient for imaging within the region of interest. In accordance withvarious embodiments, the radio frequency receive coil is in one of asingle-loop coil configuration, figure-8 coil configuration, orbutterfly coil configuration, wherein the coil is smaller than theregion of interest. In accordance with various embodiments, the radiofrequency transmit coil and the single-sided gradient coil set areconcentric about the region of interest. In accordance with variousembodiments, the magnetic resonance imaging system is a single-sidedmagnetic resonance imaging system that comprises a bore having anopening positioned about a center region of the front surface.

In accordance with various embodiments, a magnetic resonance imagingsystem is disclosed herein. In accordance with various embodiments, thesystem includes a housing having a concave front surface, a permanentmagnet for providing a static magnetic field, a radio frequency transmitcoil, and at least one gradient coil set. In accordance with variousembodiments, the radio frequency transmit coil and the at least onegradient coil set are positioned proximate to the concave front surface.In accordance with various embodiments, the radio frequency transmitcoil and the at least one gradient coil set are configured to generatean electromagnetic field in a region of interest. In accordance withvarious embodiments, the region of interest resides outside the concavefront surface. In accordance with various embodiments, the systemincludes a radio frequency receive coil for detecting signal in theregion of interest.

In accordance with various embodiments, the radio frequency transmitcoil and the single-sided gradient coil set are located on the concavefront surface. In accordance with various embodiments, the staticmagnetic field of the permanent magnet ranges from 1 mT to 1 T. Inaccordance with various embodiments, the static magnetic field of thepermanent magnet ranges from 10 mT to 195 mT. In accordance with variousembodiments, the radio frequency transmit coil comprises a first ringand a second ring that are connected via one or more capacitors and/orone or more rungs. In accordance with various embodiments, the radiofrequency transmit coil is non-planar and oriented to partially surroundthe region of interest. In accordance with various embodiments, the atleast one gradient coil set is non-planar, single-sided, and oriented topartially surround the region of interest. In accordance with variousembodiments, the at least one gradient coil set is configured to projectmagnetic field gradient in the region of interest.

In accordance with various embodiments, the at least one gradient coilset comprises one or more first spiral coils at a first position and oneor more second spiral coils at a second position, the first position andthe second position being located opposite each other about a centerregion of the at least one gradient coil set. In accordance with variousembodiments, the at least one gradient coil set has a rise time lessthan 10 μs. In accordance with various embodiments, the permanent magnethas an aperture through center of the permanent magnet. In accordancewith various embodiments, the system further includes an electromagnetconfigured to alter the static magnetic field of the permanent magnetwithin the region of interest. In accordance with various embodiments,the electromagnet has a magnetic field strength from 10 mT to 1 T. Inaccordance with various embodiments, the radio frequency receive coil isa flexible coil configured to be affixed to an anatomical portion of apatient for imaging within the region of interest. In accordance withvarious embodiments, the radio frequency receive coil is in one of asingle-loop coil configuration, figure-8 coil configuration, orbutterfly coil configuration, where the coil is smaller than the regionof interest.

In accordance with various embodiments, the radio frequency transmitcoil and the at least one gradient coil set are concentric about theregion of interest. In accordance with various embodiments, the magneticresonance imaging system is a single-sided magnetic resonance imagingsystem that comprises a magnetic resonance imaging scanner or a magneticresonance imaging spectrometer.

FIG. 1 is a schematic illustration of a magnetic resonance imagingsystem 100, in accordance with various embodiments. The system 100includes a housing 120. As shown in FIG. 1 , the housing 120 includes apermanent magnet 130, a radio frequency transmit coil 140, a gradientcoil set 150, an optional electromagnet 160, a radio frequency receivecoil 170, and a power source 180. In accordance with variousembodiments, the system 100 can include various electronic components,such as for example, but not limited to a varactor, a PIN diode, acapacitor, or a switch, including a micro-electro-mechanical system(MEMS) switch, a solid state relay, or a mechanical relay. In accordancewith various embodiments, the various electronic components listed abovecan be configured with the radio frequency transmit coil 140.

FIG. 2A is a schematic illustration of a magnetic resonance imagingsystem 200, in accordance with various embodiments. FIG. 2B illustratesan exploded view of the magnetic resonance imaging system 200. FIG. 2Cis a schematic front view of the magnetic resonance imaging system 200,in accordance with various embodiments. FIG. 2D is a schematic side viewof the magnetic resonance imaging system 200, in accordance with variousembodiments. As shown in FIGS. 2A and 2B, the magnetic resonance imagingsystem 200 includes a housing 220. The housing 220 includes a frontsurface 225. In accordance with various embodiments, the front surface225 can be a concave front surface. In accordance with variousembodiments, the front surface 225 can be a recessed front surface.

As shown in FIGS. 2A and 2B, the housing 220 includes a permanent magnet230, a radio frequency transmit coil 240, a gradient coil set 250, anoptional electromagnet 260, and a radio frequency receive coil 270. Asshown in FIGS. 2C and 2D, the permanent magnet 230 can include aplurality of magnets disposed in an array configuration. The pluralityof magnets of the permanent magnet 230 are illustrated to cover anentire surface as shown in the front view of FIG. 2C and illustrated asbars in a horizontal direction as shown in the side view of FIG. 2D. Asshown in FIG. 2A, the main permanent magnet might include an accessaperture 235 for accessing the patient from multiple sides of thesystem.

It should be understood that any use of subheadings herein are fororganizational purposes, and should not be read to limit the applicationof those subheaded features to the various embodiments herein. Each andevery feature described herein is applicable and usable in all thevarious embodiments discussed herein and that all features describedherein can be used in any contemplated combination, regardless of thespecific example embodiments that are described herein. It shouldfurther be noted that exemplary description of specific features areused, largely for informational purposes, and not in any way to limitthe design, subfeature, and functionality of the specifically describedfeature.

Permanent Magnet

As discussed herein, and in accordance with various embodiments, thevarious systems, and various combinations of features that make up thevarious system embodiments, can include a permanent magnet.

In accordance with various embodiments, the permanent magnet 230provides a static magnetic field in a region of interest 290 (alsoreferred to herein as “given field of view”). In accordance with variousembodiments, the permanent magnet 230 can include a plurality ofcylindrical permanent magnets in parallel configuration as shown inFIGS. 2C and 2D. In accordance with various embodiments, the permanentmagnet 230 can include any suitable magnetic materials, including butnot limited, to rare-earth based magnetic materials, such as forexample, Nd-based magnetic materials, and the like. As shown in FIG. 2A,the main permanent magnet might include an access aperture 235 foraccessing the patient from multiple sides of the system.

In accordance with various embodiments, the static magnetic field of thepermanent magnet 230 may vary from about 50 mT to about 60 mT, about 45mT to about 65 mT, about 40 mT to about 70 mT, about 35 mT to about 75mT, about 30 mT to about 80 mT, about 25 mT to about 85 mT, about 20 mTto about 90 mT, about 15 mT to about 95 mT and about 10 mT to about 100mT to a given field of view. The magnetic field may also vary from about10 mT to about 15 mT, about 15 mT to about 20 mT, about 20 mT to about25 mT, about 25 mT to about 30 mT, about 30 mT to about 35 mT, about 35mT to about 40 mT, about 40 mT to about 45 mT, about 45 mT to about 50mT, about 50 mT to about 55 mT, about 55 mT to about 60 mT, about 60 mTto about 65 mT, about 65 mT to about 70 mT, about 70 mT to about 75 mT,about 75 mT to about 80 mT, about 80 mT to about 85 mT, about 85 mT toabout 90 mT, about 90 mT to about 95 mT, and about 95 mT to about 100mT. In accordance with various embodiments, the static magnetic field ofthe permanent magnet 230 may also vary from about 1 mT to about 1 T,about 10 mT to about 195 mT, about 15 mT to about 900 mT, about 20 mT toabout 800 mT, about 25 mT to about 700 mT, about 30 mT to about 600 mT,about 35 mT to about 500 mT, about 40 mT to about 400 mT, about 45 mT toabout 300 mT, about 50 mT to about 200 mT, about 50 mT to about 100 mT,about 45 mT to about 100 mT, about 40 mT to about 100 mT, about 35 mT toabout 100 mT, about 30 mT to about 100 mT, about 25 mT to about 100 mT,about 20 mT to about 100 mT, and about 15 mT to about 100 mT.

In accordance with various embodiments, the permanent magnet 230 caninclude a bore 235 in its center. In accordance with variousembodiments, the permanent magnet 230 may not include a bore. Inaccordance with various embodiments, the bore 235 can have a diameterbetween 1 inch and 20 inches. In accordance with various embodiments,the bore 235 can have a diameter between 1 inch and 4 inches, between 4inches and 8 inches, and between 10 inches and 20 inches. In accordancewith various embodiments, the given field of view can be a spherical orcylindrical field of view, as shown in FIGS. 2A and 2B. In accordancewith various embodiments, the spherical field of view can be between 2inches and 20 inches in diameter. In accordance with variousembodiments, the spherical field of view can have a diameter between 1inch and 4 inches, between 4 inches and 8 inches, and between 10 inchesand 20 inches. In accordance with various embodiments, the cylindricalfield of view is approximately between 2 inches and 20 inches in length.In accordance with various embodiments, the cylindrical field of viewcan have a length between 1 inch and 4 inches, between 4 inches and 8inches, and between 10 inches and 20 inches.

It should be understood that any use of subheadings herein are fororganizational purposes, and should not be read to limit the applicationof those subheaded features to the various embodiments herein. Each andevery feature described herein is applicable and usable in all thevarious embodiments discussed herein and that all features describedherein can be used in any contemplated combination, regardless of thespecific example embodiments that are described herein. It shouldfurther be noted that exemplary description of specific features areused, largely for informational purposes, and not in any way to limitthe design, subfeature, and functionality of the specifically describedfeature.

Radio Frequency Transmit Coil

As discussed herein, and in accordance with various embodiments, thevarious systems, and various combinations of features that make up thevarious system embodiments, can also include a radio frequency transmitcoil.

FIG. 3 is a schematic view of an implementation of a magnetic imagingapparatus 300, according to various embodiments. As shown in FIG. 3 ,the apparatus 300 includes a radio frequency transmit coil 320 thatprojects the RF power outwards away from the coil 320. The coil 320 hastwo rings 322 and 324 that are connected by one or more rungs 326. Asshown in FIG. 3 , the coil 320 is also connected to a power source 350 aand/or a power source 350 b (collectively referred to herein as “powersource 350”). In accordance with various embodiments, power sources 350a and 350 b can be configured for power input and/or signal input, andcan generally be referred to as coil input. In accordance with variousembodiments, the power source 350 a and/or 350 b are configured toprovide contact via electrical contacts 352 a and/or 352 b (collectivelyreferred to herein as “electrical contact 352”), and electrical contacts354 a and/or 354 b (collectively referred to herein as “electricalcontact 354 b”) by attaching the electrical contacts 352 and 354 to oneor more rungs 326. The coil 320 is configured to project a uniform RFfield within a field of view 340. In accordance with variousembodiments, the field of view 340 is a region of interest for magneticresonance imaging (i.e., imaging region) where a patient resides. Sincethe patient resides in the field of view 340 away from the coil 320, theapparatus 300 is suitable for use in a single-sided magnetic resonanceimaging system. In accordance with various embodiments, the coil 320 canbe powered by two signals that are 90 degrees out of phase from eachother, for example, via quadrature excitation.

In accordance with various embodiments, the coil 320 includes the ring322 and the ring 324 that are positioned co-axially along the same axisbut at a distance away from each other, as shown in FIG. 3 . Inaccordance with various embodiments, the ring 322 and the ring 324 areseparated by a distance ranging from about 0.1 m to about 10 m. Inaccordance with various embodiments, the ring 322 and the ring 324 areseparated by a distance ranging from about 0.2 m to about 5 m, about 0.3m to about 2 m, about 0.2 m to about 1 m, about 0.1 m to about 0.8 m, orabout 0.1 m to about 1 m, inclusive of any separation distancetherebetween. In accordance with various embodiments, the coil 320includes the ring 322 and the ring 324 that are positionednon-co-axially but along the same direction and separated at a distanceranging from about 0.2 m to about 5 m. In accordance with variousembodiments, the ring 322 and the ring 324 can also be tilted withrespect to each other. In accordance with various embodiments, the tiltangle can be from 1 degree to 90 degrees, from 1 degree to 5 degrees,from 5 degrees to 10 degrees, from 10 degrees to 25 degrees, from 25degrees to 45 degrees, and from 45 degrees to 90 degrees.

In accordance with various embodiments, the ring 322 and the ring 324have the same diameter. In accordance with various embodiments, the ring322 and the ring 324 have different diameters and the ring 322 has alarger diameter than the ring 324, as shown in FIG. 3 . In accordancewith various embodiments, the ring 322 and the ring 324 have differentdiameters and the ring 322 has a smaller diameter than the ring 324. Inaccordance with various embodiments, the ring 322 and the ring 324 ofthe coil 320 are configured to create the imaging region in the field ofview 340 containing a uniform RF power profile within the field of view340, a field of view that is not centered within the RF-TX coil and isinstead projected outwards in space from the coil itself.

In accordance with various embodiments, the ring 322 has a diameterbetween about 10 μm and about 10 m. In accordance with variousembodiments, the ring 322 has a diameter between about 0.001 m and about9 m, between about 0.01 m and about 8 m, between about 0.03 m and about6 m, between about 0.05 m and about 5 m, between about 0.1 m and about 3m, between about 0.2 m and about 2 m, between about 0.3 m and about 1.5m, between about 0.5 m and about 1 m, or between about 0.01 m and about3 m, inclusive of any diameter therebetween.

In accordance with various embodiments, the ring 324 has a diameterbetween about 10 μm and about 10 m. In accordance with variousembodiments, the ring 324 has a diameter between about 0.001 m and about9 m, between about 0.01 m and about 8 m, between about 0.03 m and about6 m, between about 0.05 m and about 5 m, between about 0.1 m and about 3m, between about 0.2 m and about 2 m, between about 0.3 m and about 1.5m, between about 0.5 m and about 1 m, or between about 0.01 m and about3 m, inclusive of any diameter therebetween.

In accordance with various embodiments, the ring 322 and the ring 324are connected by one or more rungs 326, as shown in FIG. 3 . Inaccordance with various embodiments, the one or more rungs 326 areconnected to the ring 322 and 324 so as to form a single electricalcircuit loop (or single current loop). As shown in FIG. 3 , for example,one end of the one or more rungs 326 is connected to the electricalcontact 352 of the power source 350 and another end of the one or morerungs 326 be connected to the electrical contact 354 so that the coil320 completes an electrical circuit.

In accordance with various embodiments, the ring 322 is a discontinuousring and the electrical contact 352 and the electrical contact 354 canbe electrically connected to two opposite ends of the ring 322 to forman electrical circuit powered by the power source 350. Similarly, inaccordance with various embodiments, the ring 324 is a discontinuousring and the electrical contact 352 and the electrical contact 354 canbe electrically connected to two opposite ends of the ring 324 to forman electrical circuit powered by the power source 350.

In accordance with various embodiments, the rings 322 and 324 are notcircular and can instead have a cross section that is elliptical,square, rectangular, or trapezoidal, or any shape or form having aclosed loop. In accordance with various embodiments, the rings 322 and324 may have cross sections that vary in two different axial planes withthe primary axis being a circle and the secondary axis having asinusoidal shape or some other geometric shape. In accordance withvarious embodiments, the coil 320 may include more than two rings 322and 324, each connected by rungs that span and connect all the rings. Inaccordance with various embodiments, the coil 320 may include more thantwo rings 322 and 324, each connected by rungs that alternate connectionpoints between rings. In accordance with various embodiments, the ring322 may contain a physical aperture for access. In accordance withvarious embodiments, the ring 322 may be a solid sheet without aphysical aperture.

In accordance with various embodiments, the coil 320 generates anelectromagnetic field (also referred to herein as “magnetic field”)strength between about 1 μT and about 10 mT. In accordance with variousembodiments, the coil 320 can generate a magnetic field strength betweenabout 10 μT and about 5 mT, about 50 μT and about 1 mT, or about 100 μTand about 1 mT, inclusive of any magnetic field strength therebetween.

In accordance with various embodiments, the coil 320 generates anelectromagnetic field that is pulsed at a radio frequency between about1 kHz and about 2 GHz. In accordance with various embodiments, the coil320 generates a magnetic field that is pulsed at a radio frequencybetween about 1 kHz and about 1 GHz, about 10 kHz and about 800 MHz,about 50 kHz and about 300 MHz, about 100 kHz and about 100 MHz, about10 kHz and about 10 MHz, about 10 kHz and about 5 MHz, about 1 kHz andabout 2 MHz, about 50 kHz and about 150 kHz, about 80 kHz and about 120kHz, about 800 kHz and about 1.2 MHz, about 100 kHz and about 10 MHz, orabout 1 MHz and about 5 MHz, inclusive of any frequencies therebetween.

In accordance with various embodiments, the coil 320 is oriented topartially surround the region of interest. In accordance with variousembodiments, the ring 322, the ring 324, and the one or more rungs 326are non-planar to each other. Said another way, the ring 322, the ring324, and the one or more rungs 326 form a three-dimensional structurethat surrounds the region of interest where a patient resides. Inaccordance with various embodiments, the ring 322 is closer to theregion of interest than the ring 324, as shown in FIG. 3 . In accordancewith various embodiments, the region of interest has a size of about 0.1m to about 1 m. In accordance with various embodiments, the region ofinterest is smaller than the diameter of the ring 322. In accordancewith various embodiments, the region of interest is smaller than boththe diameter of the ring 324 and the diameter of the ring 322, as shownin FIG. 3 . In accordance with various embodiments, the region ofinterest has a size that is smaller than the diameter of the ring 322and larger than the diameter of the ring 324.

In accordance with various embodiments, the ring 322, the ring 324, orthe rungs 326 include the same material. In accordance with variousembodiments, the ring 322, the ring 324, or the rungs 326 includedifferent materials. In accordance with various embodiments, the ring322, the ring 324, or the rungs 326 include hollow tubes or solid tubes.In accordance with various embodiments, the hollow tubes or solid tubescan be configured for air or fluid cooling. In accordance with variousembodiments, each of the ring 322 or the ring 324 or the rungs 326includes one or more electrically conductive windings. In accordancewith various embodiments, the windings include litz wires or anyelectrical conducting wires. These additional windings could be used toimprove performance by lowering the resistance of the windings at thedesired frequency. In accordance with various embodiments, the ring 322,the ring 324, or the rungs 326 include copper, aluminum, silver, silverpaste, or any high electrical conducting material, including metal,alloys or superconducting metal, alloys or non-metal. In accordance withvarious embodiments, the ring 322, the ring 324, or the rungs 326 mayinclude metamaterials.

In accordance with various embodiments, the ring 322, the ring 324, orthe rungs 326 may contain separate electrically non-conductive thermalcontrol channels designed to maintain the temperature of the structureto a specified setting. In accordance with various embodiments, thethermal control channels can be made from electrically conductivematerials and integrated as to carry the electrical current.

In accordance with various embodiments, the coil 320 includes one ormore electronic components for tuning the magnetic field. The one ormore electronic components can include a varactor, a PIN diode, acapacitor, or a switch, including a micro-electro-mechanical system(MEMS) switch, a solid state relay, or a mechanical relay. In accordancewith various embodiments, the coil can be configured to include any ofthe one or more electronic components along the electrical circuit. Inaccordance with various embodiments, the one or more components caninclude mu metals, dielectrics, magnetic, or metallic components notactively conducting electricity and can tune the coil. In accordancewith various embodiments, the one or more electronic components used fortuning includes at least one of dielectrics, conductive metals,metamaterials, or magnetic metals. In accordance with variousembodiments, tuning the electromagnetic field includes changing thecurrent or by changing physical locations of the one or more electroniccomponents. In accordance with various embodiments, the coil iscryogenically cooled to reduce resistance and improve efficiency. Inaccordance with various embodiments, the first ring and the second ringcomprise a plurality of windings or litz wires.

In accordance with various embodiments, the coil 320 is configured for amagnetic resonance imaging system that has a magnetic field gradientacross the field of view. The field gradient allows for imaging slicesof the field of view without using an additional electromagneticgradient. As disclosed herein, the coil can be configured to generate alarge bandwidth by combining multiple center frequencies, each withtheir own bandwidth. By superimposing these multiple center frequencieswith their respective bandwidths, the coil 320 can effectively generatea large bandwidth over a desired frequency range between about 1 kHz andabout 2 GHz. In accordance with various embodiments, the coil 320generates a magnetic field that is pulsed at a radio frequency betweenabout 10 kHz and about 800 MHz, about 50 kHz and about 300 MHz, about100 kHz and about 100 MHz, about 10 kHz and about 10 MHz, about 10 kHzand about 5 MHz, about 1 kHz and about 2 MHz, about 50 kHz and about 150kHz, about 80 kHz and about 120 kHz, about 800 kHz and about 1.2 MHz,about 100 kHz and about 10 MHz, or about 1 MHz and about 5 MHz,inclusive of any frequencies therebetween.

It should be understood that any use of subheadings herein are fororganizational purposes, and should not be read to limit the applicationof those subheaded features to the various embodiments herein. Each andevery feature described herein is applicable and usable in all thevarious embodiments discussed herein and that all features describedherein can be used in any contemplated combination, regardless of thespecific example embodiments that are described herein. It shouldfurther be noted that exemplary description of specific features areused, largely for informational purposes, and not in any way to limitthe design, subfeature, and functionality of the specifically describedfeature.

Gradient Coil Set

As discussed herein, and in accordance with various embodiments, thevarious systems, and various combinations of features that make up thevarious system embodiments, can also include a gradient coil set.

FIG. 4 is a schematic view of an implementation of a magnetic imagingapparatus 400, according to various embodiments. As shown in FIG. 4 ,the apparatus 400 includes a gradient coil set 420 (also referred toherein as single-sided gradient coil set 420) that is configured toproject a gradient magnetic field outwards away from the coil set 420and within a field of view 430. In accordance with various embodiments,the field of view 430 is a region of interest for magnetic resonanceimaging (i.e., imaging region) where a patient resides. Since thepatient resides in the field of view 430 away from the coil set 420, theapparatus 400 is suitable for use in a single-sided MRI system.

As shown in the figure, the coil set 420 includes variously sized spiralcoils in various sets of spiral coils 440 a, 440 b, 440 c, and 440 d(collectively referred to as “spiral coils 440”). Each set of the spiralcoils 440 include at least one spiral coil and FIG. 4 is shown toinclude 3 spiral coils. In accordance with various embodiments, eachspiral coil in the spiral coils 440 has an electrical contact at itscenter and an electrical contact output on the outer edge of the spiralcoil so as to form a single running loop of electrically conductingmaterial spiraling out from the center to the outer edge, or vice versa.In accordance with various embodiments, each spiral coil in the spiralcoils 440 has a first electrical contact at a first position of thespiral coil and a second electrical contact at a second position thespiral coil so as to form a single running loop of electricallyconducting material from the first position to the second position, orvice versa.

As shown in FIG. 4 , the coil set 420 also includes an aperture 425 atits center where the spiral coils 440 are disposed around the aperture425. The aperture 425 itself does not contain any coil material withinit for generating magnetic material. The coil set 420 also includes anopening 427 on the outer edge of the coil set 420 to which the spiralcoils 440 can be disposed. Said another way, the aperture 425 and theopening 427 define the boundaries of the coil set 420 within which thespiral coils 440 can be disposed. In accordance with variousembodiments, the coil set 420 forms a bowl shape with a hole in thecenter.

In accordance with various embodiments, the spiral coils 440 form acrossthe aperture 425. For example, the spiral coils 440 a are disposedacross from the spiral coils 440 c with respect to the aperture 425.Similarly, the spiral coils 440 b are disposed across from the spiralcoils 440 d with respect to the aperture 425. In accordance with variousembodiments, the spiral coils 440 in the coil set 420 shown in FIG. 4are configured to create spatial encoding in the magnetic gradient fieldwithin the field of view 430.

As shown in FIG. 4 , the coil set 420 is also connected to a powersource 450 via electrical contacts 452 and 454 by attaching theelectrical contacts 452 and 454 to one or more of the spiral coils 440.In accordance with various embodiments, the electrical contact 452 isconnected to one of the spiral coils 440, which is then connected toother spiral coils 440 in series and/or in parallel, and one otherspiral coil 440 is then connected to the electrical contact 454 so as toform an electrical current loop. In accordance with various embodiments,the spiral coils 440 are all electrically connected in series. Inaccordance with various embodiments, the spiral coils 440 are allelectrically connected in parallel. In accordance with variousembodiments, some of the spiral coils 440 are electrically connected inseries while other spiral coils 440 are electrically connected inparallel. In accordance with various embodiments, the spiral coils 440 aare electrically connected in series while the spiral coils 440 b areelectrically connected in parallel. In accordance with variousembodiments, the spiral coils 440 c are electrically connected in serieswhile the spiral coils 440 d are electrically connected in parallel. Theelectrical connections between each spiral coil in the spiral coils 440or each set of spiral coils 440 can be configured as needed to generatethe magnetic field in the field of view 430.

In accordance with various embodiments, the coil set 420 includes thespiral coils 440 spread out as shown in FIG. 4 . In accordance withvarious embodiments, each of the sets of spiral coils 440 a, 440 b, 440c, and 440 d are configured in a line from the aperture 425 to theopening 427 so that each set of spiral coils is set apart from anotherby an angle of 90°. In accordance with various embodiments, 440 a and440 b are set at 45° from one another, and 440 c and 440 d are set at45° from one another, while 440 c is set 135° on the other side of 440 band 440 d is set 135° on the other side of 440 a. In essence, any of thesets of spiral coils 440 can be configured in any arrangement for anynumber “n” of sets of spiral coils 440.

In accordance with various embodiments, the spiral coils 440 have thesame diameter. In accordance with various embodiments, each of the setsof spiral coils 440 a, 440 b, 440 c, and 440 d have the same diameter.In accordance with various embodiments, the spiral coils 440 havedifferent diameters. In accordance with various embodiments, each of thesets of spiral coils 440 a, 440 b, 440 c, and 440 d have differentdiameters. In accordance with various embodiments, the spiral coils ineach of the sets of spiral coils 440 a, 440 b, 440 c, and 440 d havedifferent diameters. In accordance with various embodiments, 440 a and440 b have the same first diameter and 440 c and 440 d have the samesecond diameter, but the first diameter and the second diameter are notthe same.

In accordance with various embodiments, each spiral coil in the spiralcoils 440 has a diameter between about 10 μm and about 10 m. Inaccordance with various embodiments, each spiral coil in the spiralcoils 440 has a diameter between about 0.001 m and about 9 m, betweenabout 0.005 m and about 8 m, between about 0.01 m and about 6 m, betweenabout 0.05 m and about 5 m, between about 0.1 m and about 3 m, betweenabout 0.2 m and about 2 m, between about 0.3 m and about 1.5 m, betweenabout 0.5 m and about 1 m, or between about 0.01 m and about 3 m,inclusive of any diameter therebetween.

In accordance with various embodiments, the spiral coils 440 areconnected to form a single electrical circuit loop (or single currentloop). As shown in FIG. 4 , for example, one spiral coil in the spiralcoils 440 is connected to the electrical contact 452 of the power source450 and another spiral coil be connected to the electrical contact 454so that the spiral coils 440 completes an electrical circuit.

In accordance with various embodiments, the coil set 420 generates anelectromagnetic field strength (also referred to herein as“electromagnetic field gradient” or “gradient magnetic field”) betweenabout 1 μT and about 10 T. In accordance with various embodiments, thecoil set 420 can generate an electromagnetic field strength betweenabout 100 μT and about 1 T, about 1 mT and about 500 mT, or about 10 mTand about 100 mT, inclusive of any magnetic field strength therebetween.In accordance with various embodiments, the coil set 420 can generate anelectromagnetic field strength greater than about 1 μT, about 10 μT,about 100 μT, about 1 mT, about 5 mT, about 10 mT, about 20 mT, about 50mT, about 100 mT, or about 500 mT.

In accordance with various embodiments, the coil set 420 generates anelectromagnetic field that is pulsed at a rate with a rise-time lessthan about 100 μs. In accordance with various embodiments, the coil set420 generates an electromagnetic field that is pulsed at a rate with arise-time less than about 1 μs, about 5 μs, about 10 μs, about 20 μs,about 30 μs, about 40 μs, about 50 μs, about 100 μs, about 200 μs, about500 μs, about 1 ms, about 2 ms, about 5 ms, or about 10 ms.

In accordance with various embodiments, the coil set 420 is oriented topartially surround the region of interest in the field of view 430. Inaccordance with various embodiments, the spiral coils 440 are non-planarto each other. In accordance with various embodiments, the sets ofspiral coils 440 a, 440 b, 440 c, and 440 d are non-planar to eachother. Said another way, the spiral coils 440 and each of the sets ofspiral coils 440 a, 440 b, 440 c, and 440 d form a three-dimensionalstructure that surrounds the region of interest in the field of view 430where a patient resides.

In accordance with various embodiments, the spiral coils 440 include thesame material. In accordance with various embodiments, the spiral coils440 include different materials. In accordance with various embodiments,the spiral coils in set 440 a include the same first material, thespiral coils in set 440 b include the same second material, the spiralcoils in set 440 c include the same third material, the spiral coils inset 440 d include the same fourth material, but the first, second, thirdand fourth materials are different materials. In accordance with variousembodiments, the first and second materials are the same material, butthat same material is different from the third and fourth materials,which are the same. In essence, any of the spiral coils 440 can be ofthe same material or different materials depending on the configurationof the coil set 420.

In accordance with various embodiments, the spiral coils 440 includehollow tubes or solid tubes. In accordance with various embodiments, thespiral coils 440 include one or more windings. In accordance withvarious embodiments, the windings include litz wires or any electricalconducting wires. In accordance with various embodiments, the spiralcoils 440 include copper, aluminum, silver, silver paste, or any highelectrical conducting material, including metal, alloys orsuperconducting metal, alloys or non-metal. In accordance with variousembodiments, the spiral coils 440 include metamaterials.

In accordance with various embodiments, the coil set 420 includes one ormore electronic components for tuning the magnetic field. The one ormore electronic components can include a PIN diode, a mechanical relay,a solid state relay, or a switch, including a micro-electro-mechanicalsystem (MEMS) switch. In accordance with various embodiments, the coilcan be configured to include any of the one or more electroniccomponents along the electrical circuit. In accordance with variousembodiments, the one or more components can include mu metals,dielectrics, magnetic, or metallic components not actively conductingelectricity and can tune the coil. In accordance with variousembodiments, the one or more electronic components used for tuningincludes at least one of conductive metals, metamaterials, or magneticmetals. In accordance with various embodiments, tuning theelectromagnetic field includes changing the current or by changingphysical locations of the one or more electronic components. In someimplementations, the coil is cryogenically cooled to reduce resistanceand improve efficiency.

It should be understood that any use of subheadings herein are fororganizational purposes, and should not be read to limit the applicationof those subheaded features to the various embodiments herein. Each andevery feature described herein is applicable and usable in all thevarious embodiments discussed herein and that all features describedherein can be used in any contemplated combination, regardless of thespecific example embodiments that are described herein. It shouldfurther be noted that exemplary description of specific features areused, largely for informational purposes, and not in any way to limitthe design, subfeature, and functionality of the specifically describedfeature.

Electromagnet

As discussed herein, and in accordance with various embodiments, thevarious systems, and various combinations of features that make up thevarious system embodiments, can also include an electromagnet.

FIG. 5 is a schematic front view of a magnetic resonance imaging system500, according to various embodiments. In accordance with variousembodiments, the system 500 can be any magnetic resonance imagingsystem, including for example, a single-sided magnetic resonance imagingsystem that comprises a magnetic resonance imaging scanner or a magneticresonance imaging spectrometer, as disclosed herein.

As shown in FIG. 5 , the system 500 includes a housing 520 that canhouse various components, including, for example but not limited to,magnets, electromagnets, coils for producing radio frequency fields,various electronic components, for example but not limited to, forcontrolling, powering, and/or monitoring of the system 500. Inaccordance with various embodiments, the housing 520 can house, forexample, the permanent magnet 230, the radio frequency transmit coil240, and/or the gradient coil set 250 within the housing 520. Inaccordance with various embodiments, the system 500 also includes a bore535 in its center. As shown in FIG. 5 , the housing 520 also includes afront surface 525 of the system 500. In accordance with variousembodiments, the front surface 525 can be curved, flat, concave, convex,or otherwise have a straight or curvilinear surface. In accordance withvarious embodiments, the magnetic resonance imaging system 500 can beconfigured to provide a region of interest in field of view 530.

As shown in FIG. 5 , the system 500 includes an electromagnet 560disposed proximate to the front surface 525 of the system 500. Inaccordance with various embodiments, the electromagnet 560 is disposedproximate to the center of the front surface 525 on the front side ofthe system 500. In accordance with various embodiments, theelectromagnet 560 can be a solenoid coil configured to create a fieldthat either adds or subtracts from the magnetic field, for example, ofthe permanent magnet 230. In accordance with various embodiments, thisfield can create a prepolarizing field for enhancing the signal orcontrast from the nuclear magnetic resonance.

As shown in FIG. 5 , the given field of view 530 resides at the centerof the front surface 525 of the system 500. In accordance with variousembodiments, the electromagnet 560 is disposed within the given field ofview 530. In accordance with various embodiments, the electromagnet 560is disposed concentrically with the given field of view 530. Inaccordance with various embodiments, the electromagnet 560 can beinserted in the bore 535. In accordance with various embodiments, theelectromagnet 560 can be placed proximate to the bore 535. For example,the electromagnet 560 can be placed in front, back or middle of the bore535. In accordance with various embodiments, the electromagnet 560 canbe placed proximate to, or at the entrance of the bore 535.

It should be understood that any use of subheadings herein are fororganizational purposes, and should not be read to limit the applicationof those subheaded features to the various embodiments herein. Each andevery feature described herein is applicable and usable in all thevarious embodiments discussed herein and that all features describedherein can be used in any contemplated combination, regardless of thespecific example embodiments that are described herein. It shouldfurther be noted that exemplary description of specific features areused, largely for informational purposes, and not in any way to limitthe design, subfeature, and functionality of the specifically describedfeature.

Radio Frequency Receive Coil

As discussed herein, and in accordance with various embodiments, thevarious systems, and various combinations of features that make up thevarious system embodiments, can also include a radio frequency receivecoil.

Typical MR systems create a uniform field within the imaging region.This uniform field then generates a narrow band of magnetic resonancefrequencies that can then be captured by a receive coil, amplified, anddigitized by a spectrometer. Since frequencies are within a narrowwell-defined bandwidth, hardware architecture is focused on creating astatically tuned RF-RX coil with an optimal coil quality factor. Manyvariations in coil architectures have been created that explore largesingle volume coils, coil arrays, parallelized coil arrays, or bodyspecific coil arrays. However, these structures are all predicated onimaging a specific frequency close to the region of interest at highfield strengths and small as possible within a magnetic bore.

In accordance with various embodiments, an MRI system is provided thatcan include a unique imaging region that can be offset from the face ofa magnet and therefore unobstructed as compared to traditional scanners.In addition, this form factor can have a built-in magnetic fieldgradient that creates a range of field values over the region ofinterest. Lastly, this system can operate at a lower magnetic fieldstrength as compared to typical MRI systems allowing for a relaxation onthe RX coil design constraints and allowing for additional mechanismslike robotics to be used with the MRI.

The unique architecture of the main magnetic field of the MRI system, inaccordance with various embodiments, can create a different set ofoptimization constraints. Because the imaging volume now extends over abroader range of magnetic resonance frequencies, the hardware can beconfigured to be sensitive to and capture the specific frequencies thatare generated across the field of view. This frequency spread is usuallymuch larger than a single receive coil tuned to a single frequency canbe sensitive to. In addition, because the field strength can be muchlower than traditional systems, and because signal intensity can beproportional to the field strength, it is generally considered to bebeneficial to maximize the signal to noise ratio of the receive coilnetwork. Methods are therefore provided, in accordance with variousembodiments, to acquire the full range of frequencies that are generatedwithin the field of view without loss of sensitivity.

In accordance with various embodiments, several methods are providedthat can enable imaging within the MRI system. These methods can includecombining 1) a variable tuned RF-RX coil; 2) a RF-RX coil array withelements tuned to frequencies that are dependent upon the spatialinhomogeneity of the magnetic field; 3) a ultralow-noise pre-amplifierdesign; and 4) an RF-RX array with multiple receive coils designed tooptimize the signal from a defined and limited field of view for aspecific body part. These methods can be combined in any combination asneeded.

In accordance with various embodiments, a variable tuned RF-RX coil cancomprise one or more electronic components for tuning theelectromagnetic receive field. In accordance with various embodiments,the one or more electronic components can include at least one of avaractor, a PIN diode, a capacitor, an inductor, a MEMS switch, a solidstate relay, or a mechanical relay. In accordance with variousembodiments, the one or more electronic components used for tuning caninclude at least one of dielectrics, capacitors, inductors, conductivemetals, metamaterials, or magnetic metals. In accordance with variousembodiments, tuning the electromagnetic receive field includes changingthe current or by changing physical locations of the one or moreelectronic components. In accordance with various embodiments, the coilis cryogenically cooled to reduce resistance and improve efficiency.

In accordance with various embodiments, the RF-RX array can be comprisedof individual coil elements that are each tuned to a variety offrequencies. The appropriate frequency can be chosen, for example, tomatch the frequency of the magnetic field located at the specificspatial location where the specific coil is located. Because themagnetic field can vary as a function of space, as shown in FIG. 6A, thefield and frequency of the coil can be adjusted to approximately matchthe spatial location. Here the coils can be designed to image the fieldlocations B1, B2, and B3, which are physically separated along a singleaxis.

For this low field system, in accordance with various embodiments, alow-noise preamplifier can be designed and configured to leverage thelow signal environment of the MRI system. This low noise amplifier canbe configured to utilize components that do not generate significantelectronic and voltage noise at the desired frequencies (for example, <3MHz and >2 MHz). Typical junction field effect transistor designs(J-FET) generally do not have the appropriate noise characteristics atthis frequency and can create high frequency instabilities at the GHzrange that can bleed into, although several decades of dB lower, intothe measured frequency range. Since the gain of the system canpreferably be, for example, >80 dB overall, any small instabilities orintrinsic electrical noise can be amplified and degrade signalintegrity.

Referring to FIG. 6B, RF-RX coils can be designed to image specificlimited field of views based upon the target anatomy. The prostate, forexample, is about 60 millimeters deep within the human body (see FIG.6D), so to design a RX coil for prostate imaging, the coil should beconfigured to enable imaging 60 mm deep inside human body. According toBiot-Savart law, the magnetic field of a loop coil can be calculated bythe following equation,

${Bz} = {\frac{\mu_{0}}{4\pi}*\frac{2\pi*R^{2}*I}{\left( {z^{2} + R^{2}} \right)^{\frac{3}{2}}}}$

where μ0=4π*10-7 H/m is the vacuum permeability, R is the radius of theloop coil, z is distance along the center line of the coil from itscenter, and I is the current on the coil (see FIG. 6B). Assuming I=1Ampere, with the goal of locating a figure of magnetic field (Bz) atz=60 mm, the maximum position is when R is 85 mm according to the chartshown in FIG. 6C.

Based upon the geometrical constraints of the body, the loop coil can beset up at the space between the human legs upon the torso. As such, itis extremely difficult, if not impossible, to fit a 170-mm diameter coilthere. According to FIG. 6C, the Bz field value is proportional to theradius of the loop when R is less than 85 mm. As such, it isadvantageous that the coil be as large as it can be. For example, thelargest loop coil that can be placed between people is about 10 mmlarge.

As the size of the coil is limited by the space between legs, themagnetic field of a 10-mm diameter coil is generally not capable ofreaching the depth of prostate. Therefore, single coil may not be enoughfor prostate imaging thus, in this case, multiple coils could provebeneficial in getting signal from different directions. In variousembodiments of the MRI system, the magnetic field is provided in thez-direction and RF coils are sensitive to x- and y-direction. In thisexample case, a loop coil in x-y plane would not collect RF signal froma human since it is sensitive to z-direction, while a butterfly coil canbe used in this case. Then based on the location and orientation, RFcoil could be a loop coil or butterfly coil. In addition, a coil can beplaced in under the body and there is no limitation for its size.

As for the needs of multiple RX coils, in various embodiments,decoupling between them can prove beneficial for various embodiments ofan MRI system RX coil array. In those cases, each coil can be de-coupledwith the other coils, and the decoupling techniques can include, forexample, 1) geometry decoupling, 2) capacitive/inductive decoupling, and3) low-/high impedance pre-amplifier coupling.

The MRI system, in accordance with various embodiments, can have avariant magnetic field from the magnet, and its strength can varylinearly along the z direction. The RX coils can be located in differentpositions in z-direction, and each coil can be tuned to differentfrequencies, which can depend on the location of the coils in thesystem.

Based upon the simplicity of single coil loops, these coils can beconstructed from simple conductive traces that can be pre-tuned to adesired frequency and printed, for example, on a disposable substrate.This cheaply fabricated technology can allow a clinician to place the RXcoil (or coil array) upon the body at the region of interest for a givenprocedure and dispose of the coil afterwards. For example, and inaccordance with various embodiments, the RX coils can be surface coils,which can be affixed to, e.g., worn or taped to, a patient's body. Forother body parts, e.g. an ankle or a wrist, the surface coil might be asingle-loop configuration, figure-8 configuration, or butterfly coilconfiguration wrapped around the region of interest. For regions thatrequire significant penetration depth, e.g. the torso or knee, the coilmight consist of a Helmholtz coil pair. The main restriction to thereceive coil is similar to other MRI systems: the coil must be sensitiveto a plane that is orthogonal to the main magnetic field, B0, axis.

In accordance with various embodiments, the coils might be inductivelycoupled to another loop that is electrically connected to the receivepreamplifier. This design would allow for easier and unobstructed accessof the receive coils.

In accordance with various embodiments, the size of coils can be limitedby the structure of human body. For example, the coils' size should bepositioned and configured to fit in the space between human legs whenimaging the prostate.

It should be understood that any use of subheadings herein are fororganizational purposes, and should not be read to limit the applicationof those subheaded features to the various embodiments herein. Each andevery feature described herein is applicable and usable in all thevarious embodiments discussed herein and that all features describedherein can be used in any contemplated combination, regardless of thespecific example embodiments that are described herein. It shouldfurther be noted that exemplary description of specific features areused, largely for informational purposes, and not in any way to limitthe design, subfeature, and functionality of the specifically describedfeature.

Programmable Logic Controller

As discussed herein, and in accordance with various embodiments, thevarious systems, and various combinations of features that make up thevarious system embodiments, can also include a programmable logiccontroller (PLC). PLCs are industrial digital computers which can bedesigned to operate reliably in harsh usage environments and conditions.PLCs can be designed to handle these types of conditions andenvironments, not just in the external housing, but in the internalcomponents and cooling arrangements as well. As such, PLCs can beadapted for the control of manufacturing processes, such as assemblylines, or robotic devices, or any activity that requires highreliability control and ease of programming and process fault diagnosis.

In accordance with various embodiments, the system can contain a PLCthat can control the system in pseudo real-time. This controller canmanage the power cycling and enabling of the gradient amplifier system,the radio frequency transmission (transmit) system, the frequency tuningsystem, and sends a keep alive signal (e.g., a message sent by onedevice to another to check that the link between the two is operating,or to prevent the link from being broken) to the system watchdog. Thesystem watchdog can continually look for a strobe signal supplied by thecomputer system. If the computer threads stall, a strobe is missed thatcan trigger the watchdog to enter a fault condition. If the watchdogenters a fault condition, the watchdog can operated to depower thesystem.

The PLC can generally handle low level logic functions on incoming andoutgoing signals into system. This system can monitor the subsystemhealth and control when subsystems needed to be powered or enabled. ThePLC can be designed in different ways. One design example includes a PLCwith one main motherboard with four expansion boards. Due to the speedof the microcontroller on the PLC, subsystems can be managed in pseudoreal-time, while real-time applications can be handled by the computeror spectrometer on the system.

The PLC can serve many functional responsibilities including, forexample, powering on/off the gradient amplifiers (discussed in greaterdetail herein) and the RF amplifier (discussed in greater detailherein), enabling/disabling the gradient amplifiers and the RFamplifier, setting the digital and analog voltages for the RF coiltuning, and strobing the system watchdog.

As discussed above, it should be understood that any use of subheadingsherein are for organizational purposes, and should not be read to limitthe application of those subheaded features to the various embodimentsherein. Each and every feature described herein is applicable and usablein all the various embodiments discussed herein and that all featuresdescribed herein can be used in any contemplated combination, regardlessof the specific example embodiments that are described herein. It shouldfurther be noted that exemplary description of specific features areused, largely for informational purposes, and not in any way to limitthe design, subfeature, and functionality of the specifically describedfeature.

Robot

As discussed herein, and in accordance with various embodiments, thevarious systems, and various combinations of features that make up thevarious system embodiments, can also include a robot.

In some medical procedures, such as a prostate biopsy, it is typical forthe patient to endure a lengthy procedure in an uncomfortable proneposition, which often includes remaining motionless in one specific bodyposition during the entire procedure. In such long procedures, if ametallic ferromagnetic needle is used for the biopsy with guidance froman MRI system, the needle may experience attraction force from thestrong magnets of the MRI system, and thus may cause it to deviate fromits path during the length of the procedure. Even in the case of using anon-magnetic needle, the local field distortions can cause distortionsin the magnetic resonance images, and therefore, the image qualitysurrounding the needle may result in a poor quality. To avoid suchdistortions, pneumatic robots with complex compressed air mechanism havebeen designed to work in conjunction with conventional MRI systems. Eventhen, access to target anatomy remains challenging due to the formfactor of currently available MRI systems.

The various embodiments presented herein include improved MRI systemsthat are configured to use for guiding in medical procedures, including,for example, robot-assisted, invasive medical procedures. Thetechnologies, methods and apparatuses disclosed herein relate to aguided robotic system using magnetic resonance imaging as a guidance toautomatically guide a robot (generally referred to herein as “a roboticsystem”) in medical procedures. In accordance with various embodiments,the disclosed technologies combine a robotic system with magneticresonance imaging as guidance. In accordance with various embodiments,the robotic system disclosed herein is combined with other suitableimaging techniques, for example, ultrasound, x-ray, laser, or any othersuitable diagnostic or imaging methodologies.

It should be understood that any use of subheadings herein are fororganizational purposes, and should not be read to limit the applicationof those subheaded features to the various embodiments herein. Each andevery feature described herein is applicable and usable in all thevarious embodiments discussed herein and that all features describedherein can be used in any contemplated combination, regardless of thespecific example embodiments that are described herein. It shouldfurther be noted that exemplary description of specific features areused, largely for informational purposes, and not in any way to limitthe design, subfeature, and functionality of the specifically describedfeature.

Spectrometer

As discussed herein, and in accordance with various embodiments, thevarious systems, and various combinations of features that make up thevarious system embodiments, can also include a spectrometer.

A spectrometer can operate to control all real-time signaling used togenerate images. It creates the RF transmit (RF-TX) waveform, gradientwaveforms, frequency tuning trigger waveform, and blanking bitwaveforms. These waveforms are then synchronized with the RF receiver(RF-RX) signals. This system can generate frequency swept RF-TX pulsesand phase cycled RF-TX pulses. The swept RF-TX pulses allow for aninhomogeneous B1+ field (RF-TX field) to excite a sample volume moreeffectively and efficiently. It can also digitize multiple RF-RXchannels with the current configuration set to four receiver channels.However, this system architecture allows for an easy system scale-up toincrease the number of transmit and receive channels to a maximum of 32transmit channels and 16 receive channels without having to change theunderlying hardware or software architecture.

The spectrometer can serve many functional responsibilities including,for example, generating and synchronizing the RF-TX (discussed ingreater detail herein) waveforms, X-gradient waveforms, Y-gradientwaveforms, blanking bit waveforms, frequency tuning trigger waveform andRF-RX windows, and digitizing and signal processing the RF-RX datausing, for example, quadrature demodulation followed by a finite impulseresponse filter decimation such as, for example, a cascade integratingcomb (CIC) filter decimation.

The spectrometer can be designed in different ways. One design exampleincludes a spectrometer with three main components: 1) a first softwaredesign radio (SDR 1) operating with Basic RF-TX daughter cards and BasicRF-RX daughter cards; 2) a second software design radio (SDR 2)operating with LFRF TX daughter cards and Basic RF-RX daughter cards;and 3) a clock distribution module (octoclock) that can synchronize thetwo devices.

SDRs are the real-time communication device between the transmittedsignals and received MRI signals. They can communicate over 10 Gbitoptical fiber to the computer using a Small Form-factor Pluggable Plustransceiver (SFP+) communication protocol. This communication speed canallows the waveforms to be generated with high fidelity and highreliability.

Each SDR can include a motherboard with an integrated field-programmablegate array (FPGA), digital to analog converters, analog to digitalconverters, and four module slots for integrating differentdaughtercards. Each of these daughtercards can function to change thefrequency response of the associated TX or RX channel. In accordancewith various embodiments, the system can utilizes many variationsdaughtercards including, for example, a Basic RF version, and a lowfrequency (LF) RF version. The Basic RF daughtercards can be used forgenerating and measuring RF signals. The LF RF version can be used forgenerating gradient, trigger and blanking bit signals.

The octoclock can be used to synchronize a multi-channel SDR system to acommon timing source while providing high-accuracy time and frequencyreference distribution. It can do so, for example, with 8-way time andfrequency distribution (1 PPS and 10 MHz). An example of an octoclock isthe Ettus Octoclock CDA, which can distribute a common clock to up toeight SDRs to ensure phase coherency between the two or more SDRsources.

It should be understood that any use of subheadings herein are fororganizational purposes, and should not be read to limit the applicationof those subheaded features to the various embodiments herein. Each andevery feature described herein is applicable and usable in all thevarious embodiments discussed herein and that all features describedherein can be used in any contemplated combination, regardless of thespecific example embodiments that are described herein. It shouldfurther be noted that exemplary description of specific features areused, largely for informational purposes, and not in any way to limitthe design, subfeature, and functionality of the specifically describedfeature.

RF AMP/Gradient AMP

As discussed herein, and in accordance with various embodiments, thevarious systems, and various combinations of features that make up thevarious system embodiments, can also include a radio frequency amplifier(RF amplifier) and a gradient amplifier.

A RF amplifier is a type of electronic amplifier that can converts alow-power radio-frequency signal into a higher power signal. Inoperation, the RF amplifier can accept signals at low amplitudes andprovide, for example, up to 60 dB of gain with a flat frequencyresponse. This amplifier can accept three phase AC input voltage and canhave a 10% max duty cycle. The amplifier can be gated by a 5V digitalsignal so that unwanted noise is not generated when the MRI is receivingsignal.

In operation, a gradient amplifier can increase the energy of the signalbefore it reaches the gradient coils such that the field strength can beintense enough to produce the variations in the main magnetic field forlocalization of the later received signal. The gradient amplifier canhave two active amplification channels that can be controlledindependently. Each channel can send out current to either the X or Ychannel respectively. The third axis of spatial encoding is generallyhandled by a permanent gradient in the main magnetic field (B0). Withvarying combinations of pulse sequences, the signal can be localized inthree dimensions and reconstructed to create an object.

It should be understood that any use of subheadings herein are fororganizational purposes, and should not be read to limit the applicationof those subheaded features to the various embodiments herein. Each andevery feature described herein is applicable and usable in all thevarious embodiments discussed herein and that all features describedherein can be used in any contemplated combination, regardless of thespecific example embodiments that are described herein. It shouldfurther be noted that exemplary description of specific features areused, largely for informational purposes, and not in any way to limitthe design, subfeature, and functionality of the specifically describedfeature.

Display/GUI

As discussed herein, and in accordance with various embodiments, thevarious systems, and various combinations of features that make up thevarious system embodiments, can also include a display in the form of,for example, a graphical user interface (GUI). In accordance withvarious embodiments, the GUI can take any contemplated form necessary toconvey the information necessary to run magnetic resonance imagingprocedures.

Further, it should be appreciated that the display may be embodied inany of a number of other forms, such as, for example, a rack-mountedcomputer, mainframe, supercomputer, server, client, a desktop computer,a laptop computer, a tablet computer, hand-held computing device (e.g.,PDA, cell phone, smart phone, palmtop, etc.), cluster grid, netbook,embedded systems, or any other type of special or general purposedisplay device as may be desirable or appropriate for a givenapplication or environment.

The GUI is a system of interactive visual components for computersoftware. A GUI can display objects that convey information, andrepresent actions that can be taken by the user. The objects changecolor, size, or visibility when the user interacts with them. GUIobjects include, for example, icons, cursors, and buttons. Thesegraphical elements are sometimes enhanced with sounds, or visual effectslike transparency and drop shadows.

A user can interact with a GUI using an input device, which can include,for example, alphanumeric and other keys, mouse, a trackball or cursordirection keys for communicating direction information and commandselections to a processor and for controlling cursor movement on thedisplay. An input device may also be the display configured withtouchscreen input capabilities. This input device typically has twodegrees of freedom in two axes, a first axis (i.e., x) and a second axis(i.e., y), that allows the device to specify positions in a plane.However, it should be understood that input devices allowing for 3dimensional (x, y and z) cursor movement are also contemplated herein.

In accordance with various embodiments, the touchscreen, or touchscreenmonitor, can serves as the primary human interface device that allows auser to interact with the MRI. The screen can have a projectedcapacitive touch sensitive display with an interactive virtual keyboard.The touchscreen can have several functions including, for example,displaying the graphical user interface (GUI) to the user, relaying userinput to the system's computer, and starting or stopping a scan.

In accordance with various embodiments, GUI views can be typicallyscreens displayed (Qt widgets) to the user with appropriate buttons,edit fields, labels, images, etc. These screens can be constructed usinga designer tool such as, for example, the Qt designer tool, to controlplacement of widgets, their alignment, fonts, colors, etc. A userinterface (UI) sub controller can possess modules configured to controlthe behavior (display and responses) of the respective view modules.

Several application utilities (App Util) modules can performs specificfunctions. For example, S3 modules can handle data communication betweenthe system and, for example, Amazon Web Services (AWS). Event Filterscan be present to ensure valid characters are displayed on screen whenuser inputs are required. Dialog messages can be used to show variousstatus, progress messages or require user prompts. Moreover, a systemcontroller module can be utilized to handle coordination between the subcontroller modules, and key data processing blocks in the system, thepulse sequence generator, pulse interpreter, spectrometer andreconstruction.

It should be understood that any use of subheadings herein are fororganizational purposes, and should not be read to limit the applicationof those subheaded features to the various embodiments herein. Each andevery feature described herein is applicable and usable in all thevarious embodiments discussed herein and that all features describedherein can be used in any contemplated combination, regardless of thespecific example embodiments that are described herein. It shouldfurther be noted that exemplary description of specific features areused, largely for informational purposes, and not in any way to limitthe design, subfeature, and functionality of the specifically describedfeature.

Processing Module

As discussed herein, and in accordance with various embodiments, thevarious workflows or methods, and various combinations of steps thatmake up the various workflow or method embodiments, can also include aprocessing module.

In accordance with various embodiments, a processing module serves manyfunctions. For example, a processing module can generally operate toreceive signal data acquired during the scan, process the data, andreconstruct those signals to produce an image that can be viewed (forexample, via a touchscreen monitor that displays a GUI to the user),analyzed and annotated by system users. Generally, to create an image,an NMR signal must be localized in three-dimensional space. Magneticgradient coils localize the signal and are operated before or during theRF acquisition. By prescribing a RF and gradient coil applicationsequence, called a pulse sequence, the signals acquired correspond to aspecific magnetic field and RF field arrangement. Using mathematicaloperators and image reconstruction techniques, arrays of these acquiredsignals can be reconstructed into an image. Usually these images aregenerated from simple linear combinations of magnetic field gradients.In accordance with various embodiments, the system can operate toreconstruct the acquired signals from a-priori knowledge of, forexample, the gradient fields, RF fields, and pulse sequences.

In accordance with various embodiments, the processing module can alsooperate to compensate for patient motion during a scan procedure. Motion(e.g., beating heart, breathing lungs, bulk patient movement) is one ofthe most common sources of artifacts in MRI, with such artifactsaffecting image quality by leading to misinterpretations in the imagesand a subsequent loss in diagnostic quality. Therefore, motioncompensation protocols can help address these issues at minimal cost intime, spatial resolution, temporal resolution, and signal-to-noiseratio.

In accordance with various embodiments, the processing module mightinclude artificial intelligence machine learning modules designed todenoise the signal and improve the image signal-to-noise ratio.

In accordance with various embodiments, the processing module can alsooperate to assist clinicians in planning a path for subsequent patientintervention procedures, such as biopsy. In accordance with variousembodiments, a robot can be provided as part of the system to performthe intervention procedure. The processing module can communicateinstructions to the robot, based on image analysis, to properly access,for example, the appropriate region of the body requiring a biopsy.

It should be understood that any use of subheadings herein are fororganizational purposes, and should not be read to limit the applicationof those subheaded features to the various embodiments herein. Each andevery feature described herein is applicable and usable in all thevarious embodiments discussed herein and that all features describedherein can be used in any contemplated combination, regardless of thespecific example embodiments that are described below. It should furtherbe noted that exemplary description of specific features are used,largely for informational purposes, and not in any way to limit thedesign, subfeature, and functionality of the specifically describedfeature.

Chirped Magnetic Resonance Imaging Module

For wide bandwidth pulses, two recognized ways to increase the bandwidthof a radio frequency (RF) pulse beyond the limits of the Fourierrelationship between its length and bandwidth are composite pulses andadiabatic pulses. Adiabatic pulses, in particular, can be used inimaging with the typical goals of compensating for RF fieldimperfections and compensating for permanent magnetic field gradients.An example of a relevant adiabatic pulse is a chirp pulse. Known uses ofthe chirp pulse serve to encode spatial information using the permanentgradient as well as a pulsed electromagnetic gradient.

The disclosed systems and methods in accordance with various embodimentsas described herein relate to improved approaches to collect NMR spectraand MR images in inhomogeneous fields using wide bandwidth pulses, viaan RF chirp pulse.

For multi-slice excitation methods for imaging inhomogeneous fields, ifthe bandwidth of an RF pulse cannot be increased or should not beincreased (e.g., via wide band pulses), methods exists for collectinginformation from the entire imaging volume. A relevant way is to tunethe resonance frequency of the RF coil to a different frequency when auser wants to measure a different part of space. This allows one tosample the entire imaging field of view even if the bandwidth of the RFpulses are narrower than the frequency range of the entire field ofview. As a result, of this multi-slice excitation method, one can imagea three-dimensional (3D) volume by exciting multiple slices along oneaxis and then phase encode along the other two axes. Using readoutpulses in a system with a strong permanent gradient is inadvisablebecause the axis of the readout will be tilted by the permanentgradient. The problem with such techniques is that each slice must bemeasured one at a time and the thinness of each slice results in theignoring of the slice selection axis, thus resulting in the projectionof a 3D voxel onto a 2D plane, with the axes of the 2D plane being phaseencoded. Therefore, having to phase encode both axes while alsocollecting each slice one by one severely slows the rate of imageacquisition.

The disclosed systems and methods in accordance with various embodimentsas described herein relate to improved approaches to collect NMR spectraand MR images in inhomogeneous fields using multi-slice excitationmethods with a faster rate of image acquisition than currently exists inthe art.

In accordance with various embodiments, inhomogeneity can be consideredthe degree of lack of homogeneity, for example the fractional deviationof the local magnetic field from the average value of the field.

In accordance with various embodiments, a pulse sequence diagramillustrates the steps of basic hardware activity that are incorporatedinto a pulse sequence using multiple lines, each representing adifferent component. For example, the radio frequency transmittercomponent can be represented on the top line of a pulse sequencediagram, slice selection gradient on the second line, phase encodinggradient on the third line, and frequency encoding gradient/readoutgradient on the fourth or bottom line.

FIG. 7A is an example schematic pulse sequence diagram 700 a for atwo-dimensional (2D) pulse sequence, in accordance with variousembodiments. For pulse sequence diagrams of a 2D-pulse sequence, asshown in FIG. 7A, slice selection and signal detection are repeated induration, relative timing and amplitude, each time the sequence isrepeated. Durations of the slice selection pulses may range from 70microseconds to 10 milliseconds while the amplitude of the sliceselection pulses may be modified to reach flip angles 1 to 180 degrees.The duration of the acquisition window will vary depending on thestrength of the readout gradient applied during it. Acquisitiondurations may range from 10 microseconds to 10 milliseconds, with thenumber of points acquired during this time ranging from 16 to 512. Foreach executed sequence, a single-phase encoding component is present. Adeviation above or below the horizontal line generally indicates agradient pulse. Pulse diagrams can indicate simultaneous componentactivities such as the RF pulse and slice selection gradient as non-zerodeviations from both lines at the same horizontal position. Simpledeviations from zero show constant amplitude gradient pulse. Gradientamplitudes that change during the measurement, e.g. phase encoding arerepresented on the diagram.

FIG. 7B is an example schematic pulse sequence diagram 700 b for athree-dimensional pulse sequence, in accordance with variousembodiments. As illustrated in FIG. 7B, a 3D-pulse sequence 700 b shownincludes volume excitation and signal detection that are repeated induration, relative timing and amplitude, each time the sequence isrepeated. In the case of a 3D-pulse sequence, two-phase encodingcomponents are present, one in the phase encoding direction and theother in slice selection direction (irrespectively incremented inamplitude) in each time the sequence is executed.

It is well known that inhomogeneities of the static magnetic field,e.g., permanent gradient field, which is also referred to herein asinhomogeneous permanent gradient field, produced by the scanner as wellas by object susceptibility, is difficult to avoid in magnetic resonanceimaging (MRI). Typically, the inhomogeneity of the field is a nuisanceto be avoided and rarely is the inhomogeneous field a source of spatialinformation. The large value of gyromagnetic coefficient can cause asignificant frequency shift in field inhomogeneity of even a few partsper million, which in turn causes distortions in both geometry andintensity of the magnetic resonance (MR) images. Manufacturers willalways strive to homogenize the magnetic field as much as possible,especially at the core of the scanner. Even with an ideal magnet,inhomogeneity remains to some degree, which can also be caused by thesusceptibility of the imaging object. The geometrical distortion(displacement of the pixel locations) is important e.g., for some casesas stereotactic surgery. The second problem is the undesired changes inthe intensity or brightness of pixels, which may cause problems indetermining different tissues and reduce the maximum achievable imageresolution.

Relevant methods for imaging in inhomogeneous fields include use of widebandwidth pulses and multi-slice excitation. Both however deal with thechallenge of imaging in an inhomogeneous permanent field. Wide bandwidthpulses, for example, affect a wide range of frequencies. Bandwidths ofthe wide bandwidth pulses may range from about 1 kHz to about 1 MHz. Inaccordance with various embodiments, the bandwidth may range from 1 kHzto 10 kHz, 10 kHz to 40 kHz, 40 kHz to 100 kHz, 100 kHz to 400 kHz, and400 kHz to 1 MHz, or any ranges of bandwidth thereof. Examples of RFpulses that can have such bandwidths include chirped pulses, adiabatichalf passage pulses and composite hard pulses. If a field isinhomogeneous, then increasing the bandwidth of a pulse means that theRF pulse may affect more of a sample. There are many ways to increasethe bandwidth of an RF pulse beyond the limits of the Fourierrelationship between its length and bandwidth. Two notable ways arecomposite pulses and adiabatic pulses.

Composite pulses are conventional RF pulses appended to one another inan order, often with phase shifts between the appended pulses. Bycombining RF pulses in this way, it is possible to compensate for theirimperfections. Doing so also makes the bandwidth of the composite pulsegreater than the bandwidth of the pulses used to make it. This makescomposite pulses ideal for use in inhomogeneous magnetic fields.

Adiabatic pulses excite, invert or refocus magnetization by a differentmeans than conventional RF pulses. Instead of abruptly changing theeffective magnetic field experienced by the magnetization, adiabaticpulses instead change the effective field gradually, dragging themagnetization along with the field as it changes. The effective field ischanged by altering the frequency of the RF pulse. The duration of thesepulses can range from 100 microseconds to 20 milliseconds. Themagnetization will tend to be aligned with the direction of theeffective field, until the RF pulse is on resonance with themagnetization, where the adiabatic condition will be violated, allowingfor adiabatic excitation. In the case of adiabatic inversion, themagnetization will always follow the direction of the effective field.This allows for RF pulses with much wider bandwidths than conventionalRF pulses, among other advantages. One can implement adiabatic pulses inoil well logging to excite a wide bandwidth, since oil well logging canoccur in inhomogeneous fields. One can also implement adiabatic pulsesin imaging, usually to compensate for RF field imperfections but also tocompensate for permanent magnetic field gradients.

One example of use of an adiabatic pulse to compensate for a permanentgradient is multi-scan extension of cross-term spatiotemporal encoding(xSPEN), a pulse sequence using a type of adiabatic pulse referred to asa chirp pulse. The chirp pulse is one where different wavelengths orcolors are not distributed uniformly over the temporal envelope of thepulse. As a result, this pulse affects different parts of space atdifferent times, creating signals that refocus at different points alongthe acquisition. Exploiting these characteristics of a chirp pulse canallow for the encoding of spatial information using the permanentgradient and a pulsed gradient.

For multi-slice excitation methods for imaging inhomogeneous fields, ifthe bandwidth of an RF pulse cannot be increased or should not beincreased (e.g., via wide band pulses), methods exists for collectinginformation from the entire imaging volume. A relevant way is to tunethe resonance frequency of the RF coil to a different frequency when auser wants to measure a different part of space. This allows one tosample the entire imaging field of view even if the bandwidth of the RFpulses are narrower than the frequency range of the entire field ofview. As a result of this multi-slice excitation method, one can image a3D volume by exciting multiple slices along one axis and then phaseencoding along the other two axes, which is necessary to phase encodealong both axes due to the strong gradient present in the magnetic fieldgenerally produced by such multi-slice excitation methods. Phaseencoding along two axes is done by applying a magnetic field gradientalong two orthogonal axes when not acquiring signal. By arraying thegradient strength or duration during this phase encoding step, it ispossible to encode images along two additional dimensions, with thethird being encoded during the signal acquisition step. The problem withsuch techniques is that each slice must be measured one at a time andthe thinness of each slice results in the ignoring of the sliceselection axis, thus resulting in the projection of a 3D voxel onto a 2Dplane, with the axes of the 2D plane being phase encoded. Therefore,having to phase encode both axes while also collecting each slice one byone severely slows the rate of image acquisition.

In accordance with various embodiments, the technologies describedherein are directed to collect NMR spectra and MR images ininhomogeneous fields using multi-slice excitation methods with a fasterrate of image acquisition than currently exists in the art. Therefore,Applicant has recognized that solutions are lacking for implementingwide bandwidth pulses (e.g., adiabatic pulses) via chirp pulses forscanner types that seek to avoid utilizing a pulse gradient to encodethe requisite spatial information. Applicant has further recognized thatsolutions are lacking for implementing multi-slice excitation methods inscanners that result in a faster rate of image acquisition thancurrently exists in the art.

If the permanent gradient in a single sided MRI can be made linear or atleast bijective (e.g., one-to-one correspondence between data sets),then the information from that gradient can be used to encode spatialinformation. To use the permanent gradient as an encoding gradient, aspin echo must be acquired in the field produced by that gradient. AFourier transform or nonlinear reconstruction of the time domain data ofthis spin echo can then be used to generate a 1 dimensional profile ofthe object or patient along the direction of the gradient of thepermanent field. For this to be useful, a significant fraction of themagnetization within that gradient must be accessible to RF pulses.

In accordance with various embodiments, a scanner is provided that has apermanent gradient, specially optimized using small magnet elementsarranged in a pattern to create a weak enough gradient to allow for awide RF bandwidth excitation up to about 200 kHz but strong enough forspatial encoding in the permanent magnet direction. The scanner can alsohave an RF coil that has multiple legs to increase overall fieldstrength that allows for strong and uniform excitation of a wide rangeof bandwidth with adiabatic pulses. This allows Promaxo to use a uniqueMRI pulse sequence for 3D encoding.

The basis of the pulse sequence used, in accordance with variousembodiments herein, is that the slice select gradient, which ispermanent, is also used as a readout gradient. In other words, theinformation about the slice axis is not projected onto a 2D plane. Thisis advantageous particularly for scanners that use permanent gradientsprimarily, as using pulsed readout gradients will likely distort theimage. The axes besides the slice select axis must be phase encoded forgood image fidelity.

There are many ways to implement the pulse sequence in accordance withvarious embodiments herein. These include the use of a wide bandwidthpulse, via an adiabatic pulse such as, for example, a chirped pulse forexcitation and refocusing. Chirped pulses, for example, can be used forincreasing the bandwidth. By using, for example, a chirp pulse, a widebandwidth can be excited and the frequencies within that bandwidth cancontain spatial information along one axis.

FIG. 8 is a schematic pulse sequence diagram 800 for a system withchirped pulses and a permanent slice selection gradient, in accordancewith various embodiments. As illustrated in FIG. 8 , an approach forusing wide band pulses (e.g., chirped pulses) for collecting magneticresonance images or spectra using a single sided MRI is provided, inaccordance with various embodiments. For example, if a permanentmagnetic gradient field, such as an inhomogeneous magnetic field isalong an axis in the z direction, two phase encodes 810 and 820 can beused in the x and y-axes, as shown in the pulse diagram 800. In theexample illustrated in FIG. 8 , a single echo can be used. Additionally,the pulse diagram 800 includes two chirped pulses 830 and 840 that canbe used and calibrated such that all magnetization refocuses at the samemoment, e.g., at the precise time period, during an acquisition 850. Assuch, the second pulse 840 can be half the length of the first pulse 830as illustrated in pulse diagram 800, if both pulses have the same orsubstantially similar bandwidth, in accordance with various embodiments.

The bandwidth of these pulses may range from 1 kHz to 10 kHz, 10 kHz to40 kHz, 40 kHz to 100 kHz, 100 kHz to 400 kHz, and 400 kHz to 1 MHz, orany ranges of bandwidth thereof. The magnetization affected by thechirped pulse can be, for example, phase encoded along two orthogonalaxes or along just one axis for 2D images. In various embodiments, theentire imaging volume is encoded at once. In various embodiments,portions of the imaging volume are encoded one at a time. The signalthat this produces is encoded along z for the readout and x and y forphase encodes. Doing so allows one to image an entire volume morequickly. The slice thickness of the volume can be increased with postprocessing to increase the signal to noise ratio.

Therefore, in view of the above, Applicant has discovered a way tocollect NMR spectra and MR images in inhomogeneous fields using aspecific wide-band pulse (e.g., chirp pulse) in combination withmulti-slice excitation methods in specific MRI scanners (e.g.,single-sided MRIs) with a faster rate of image acquisition without theneed for a pulsed gradient. This method allows for imaging an entirevolume much more quickly than would otherwise be possible with amulti-slice acquisition. In addition, by using the slice select gradientas a readout, no information along the z-axis is lost. In view of thetechnologies disclosed in accordance with various embodiments, thedisclosed implementation methods overcome existing challenges incombining the two methods. For example, some of the overcome challengesmay include difficulty in implementing chirp pulses for imaging whilecompensating for their unusual behavior, designing a permanent fieldthat is useful for imaging, interleaving the data slices excited by thechirp pulse for efficient signal averaging, and/or collapsing 3dimensional data into a series of 2 dimensional slices efficiently whenthe third dimension is directly measured.

The speedup can be best appreciated by calculating how many slices areneeded to image a normal field of view. For example, in accordance withvarious embodiments, the field of view (also referred to herein asregion of interest) in the scanner discussed herein is a 4 to 12 inchdiameter sphere. The example scanner can be capable of producingconventional slice selection pulses with a thickness ranging from 0.5 to5 mm, which means that, for example, approximately 34 slices would beselected to cover the entire field of view. The same scanner is alsoable to produce chirped pulses that excite slices with thickness of oneinch, meaning that only four slices are needed to cover the whole fieldof view, provided that the slice direction is treated as a readout aswell. That would be a speedup of approximately 8.5, with possiblelimitations on speedup primarily due to the hardware of the scanner.With wide bandwidth receive and transmit coils, equal to the bandwidthof the field of view, it is possible to select the entire imaging volumewith one slice.

FIG. 9 illustrates example pulse sequences, in accordance with variousembodiments. As illustrated in FIG. 9 , some example of the digitalwaveforms generated by a system computer and sent to the software designradio (SDR). A signal sequence 910 shown in the top channel is the radiofrequency transmit (RFTx) channel, which has all the waveforms sent to atransmit system (TX) segment of the RF system. In this example, allpulses in the RFTx channel are chirped pulses, with identicalbandwidths, but differing durations. In accordance with variousembodiments, the pulses generated are not mixed with a carrier wave inthis iteration, meaning that their center frequency is 0 Hz. Oncegenerated, the pulses are mixed with a carrier wave in the SDR, changingtheir center frequency to the frequency needed to meet the Larmorfrequency of the system, in accordance with various embodiments.

As illustrated in FIG. 9 , a signal sequence 920 is the radio frequencyreceive (RFRx) channel. Unlike the RFTx channel, this channel is notconverted into an analog signal. Instead, this channel is a series ofinstructions for the SDR for when to digitize the analog signal it isreceiving from the receive system (RX) section of the RF system. Inaccordance with various embodiments, the SDR is always receiving somesignal from the RX section, but only the signal collected when the RFRxchannel is set to 1 is relevant for imaging.

Further illustrated in FIG. 9 , signal sequences 930 and 940 shown inthe bottom two channels are the gradient channels. In accordance withvarious embodiments, these signal sequences 930 and 940 correspond tothe waveforms that are sent to the gradient coils, after being amplifiedby a gradient amplifier. The gradients are responsible for encodingspatial information in the signal collected, in accordance with variousembodiments.

FIG. 10 illustrates an example position of patient for imaging in amagnetic resonance imaging system 1000, according to variousembodiments. As illustrated in FIG. 10 , the receive (Rx) coil 1070 canbe placed on a patient 1100. In accordance with various embodiments, thereceive coil 1070 can be one of a single-loop coil configuration,figure-8 coil configuration, or butterfly coil configuration. Asillustrated in FIG. 10 , the receive coil 1070 is a 3-loop coil that isplaced on an anatomical portion of the patient 1100. In accordance withvarious embodiments, the signal acquired by the receive coil 1070 can besent to the RX section of the RF system.

In accordance with various embodiments, a method for performing achirped MRI scan includes the following steps. In a first step, thepatient is positioned so that the relevant part of their body is placedin the field of view. Then, a receive coil or coil array is placed onthe patient. Different parts of the body can require different receivecoil arrays. In accordance with various embodiments, the design of thesearrays varies. In accordance with various embodiments, some designs haveall coils with the same tune, which is changed with the tuning box. Inaccordance with various embodiments, others have an array of coils whereeach has a separate, static tune. Regardless of the design, the receivecoils are placed so that their spatial sensitivity overlaps with thefrequencies that they are sensitive to. Once the patient and the receivecoils are positioned, a signal is acquired to confirm their placement.Signal is acquired by sending out two pulses from the SDR to the TXsection of the RF system. These two pulses are both chirped pulses,designed to induce a signal in the patient which will be picked up bythe receive coils on their body. These signals are then sent from thereceive coils to the RX section of the RF system. If a signal isdetected, the scan proceeds to its next step. In the next phase, animage is taken of the patient to confirm that they have been placed inthe correct position. To collect an image, a sequence of chirped pulsesare applied to the patient. These pulses are sent through the TX sectionof the RF system. In between applications of these chirped pulses,signal is acquired from the receive coils, through the RX section of theRF system. Also, gradient pulses are sent to the system to encodespatial information to the signal. Once the position of the patient isconfirmed, a full image is taken. The full image is collected in amanner similar to the image used to confirm the position of the patient.The only difference is that the full image will be higher resolution andso will take longer to acquire.

In accordance with various embodiments, a magnetic resonance imagingsystem is provided. In accordance with various embodiments, the systemincludes a radio frequency receive system comprising a radio frequencyreceive coil configured to be placed proximate a target subject. Inaccordance with various embodiments, the receive system is configured todeliver a signal of a target subject for forming a magnetic resonanceimage of the target subject, wherein the signal comprises at least twochirped pulses. In accordance with various embodiments, the systemincludes a housing, wherein the housing comprises a permanent magnet forproviding an inhomogeneous permanent gradient field. In accordance withvarious embodiments, the imaging system is configured to apply amulti-slice excitation along the inhomogeneous permanent gradient field,a radio frequency transmit system configured to deliver a sequence ofchirped pulses, and a single-sided gradient coil set configured todeliver a plurality of gradient pulses orthogonal to the inhomogeneouspermanent gradient field.

In accordance with various embodiments, the system further includes apower source, wherein the power source is configured to flow currentthrough at least one of the radio frequency transmit system, and thesingle-sided gradient coil set, to generate an electromagnetic field ina region of interest, wherein the region of interest encompasses thetarget subject. In accordance with various embodiments, the region ofinterest has a diameter of 4 to 12 inches.

In accordance with various embodiments, the imaging system is configuredto apply a multi-slice excitation comprising exciting multiple slicesalong an axis of the inhomogeneous permanent gradient field, whereineach of the multiple slices has a bandwidth that is similar to the broadbandwidth of the chirped pulses. In accordance with various embodiments,the chirped pulses comprise identical bandwidths and differingdurations. In accordance with various embodiments, the chirped pulseshave a bandwidth ranging from 1 kHz to 10 kHz, 10 kHz to 40 kHz, 40 kHzto 100 kHz, 100 kHz to 400 kHz, 400 kHz to 1 MHz, or any ranges ofbandwidth thereof.

In accordance with various embodiments, the chirped pulses areconfigured to produce a 1-dimensional signal along an axis of theinhomogeneous permanent gradient field. In accordance with variousembodiments, the 1-dimensional signal is the first 1-dimensional signal,and the gradient pulses are configured to produce a second 1-dimensionalsignal and a third 1-dimensional signal that are orthogonal to eachother and to the axis of the inhomogeneous permanent gradient field.

In accordance with various embodiments, the gradient pulses areconfigured for encoding spatial information to the signal. In accordancewith various embodiments, the combination of the inhomogeneous permanentgradient field and the chirped pulses are configured for slice selectionin the inhomogeneous permanent gradient and a frequency encodinggradient. In accordance with various embodiments, the target subject isan anatomical portion of a body.

In accordance with various embodiments, the receive coil includes anarray of receive coils and each of the array of receive coils isconfigured for specific anatomical portion of a body. In accordance withvarious embodiments, the chirped pulses induce a signal in the targetsubject, and the receive coil is configured to receive the signal. Inaccordance with various embodiments, each of the at least two chirpedpulses are split into two components that are 90 degrees out of phase.In accordance with various embodiments, the transmit system furthercomprises two separate ports configured to generate the at least twochirped pulses.

In accordance with various embodiments, the magnetic resonance imagingsystem further includes a signal conditioning box and a control system,wherein the signal conditioning box is configured to turn the controlsystem on and off with a blanking signal. In accordance with variousembodiments, the magnetic resonance imaging system further includes aradio frequency amplifier, the amplifier enabled and disabled when thecontrol system is turned on and off with the blanking signal.

In accordance with various embodiments, the radio frequency transmitsystem includes a transmit coil that is non-planar and oriented topartially surround the region of interest.

In accordance with various embodiments, the magnetic resonance imagingsystem further includes a tuning box, wherein the tuning box isconfigured to alter the frequency response of the transmit coil.

In accordance with various embodiments, the gradient coil set isnon-planar and oriented to partially surround the region of interest,and wherein the gradient coil set is configured to project a magneticfield gradient to the region of interest.

In accordance with various embodiments, the receive coil is a flexiblecoil configured to be affixed to an anatomical portion of a patient forimaging within the region of interest.

In accordance with various embodiments, the receive coil is in one of asingle-loop coil configuration, figure-8 coil configuration, orbutterfly coil configuration, wherein the receive coil is smaller thanthe region of interest. In accordance with various embodiments, thetransmit coil and the gradient coil set are concentric about the regionof interest.

FIG. 11 is a schematic illustration of an example magnetic resonanceimaging system 1100, in accordance with various embodiments. The system1100 includes an imaging system 1110, a power source 1180, and a controlsystem 1190. As shown in FIG. 11 , the imaging system 1110 includes ahousing 1120 and a radio frequency receive system 1170. As shown in FIG.11 , the housing 1120 includes a permanent magnet 1130, a radiofrequency transmit system 1140, a gradient coil set 1150, and anoptional electromagnet 1160. In accordance with various embodiments, thesystem 1100 can include various electronic components, such as forexample, but not limited to a varactor, a PIN diode, a capacitor, or aswitch, including a micro-electro-mechanical system (MEMS) switch, asolid state relay, or a mechanical relay. In accordance with variousembodiments, the various electronic components listed above can beconfigured with the radio frequency transmit system 1140.

In accordance with various embodiments, since the example system 1100 asshown and described with respect to FIG. 11 is similar to, or includesimilar components of, the example system 100 as shown and describedwith respect to FIG. 1 , each of the components will not be described infurther detail unless specified otherwise. For example, the radiofrequency transmit system 1140 can include a radio frequency transmitcoil that can be identical, or substantially identical, to the radiofrequency transmit coil 140, in accordance with various embodiments.Similarly, the radio frequency receive system 1170 can include a radiofrequency receive coil that can be identical, or substantiallyidentical, to the radio frequency receive coil 170, in accordance withvarious embodiments.

It should be understood that any use of subheadings herein are fororganizational purposes, and should not be read to limit the applicationof those subheaded features to the various embodiments herein. Each andevery feature described herein is applicable and usable in all thevarious embodiments discussed herein and that all features describedherein can be used in any contemplated combination, regardless of thespecific example embodiments that are described herein. It shouldfurther be noted that exemplary description of specific features areused, largely for informational purposes, and not in any way to limitthe design, subfeature, and functionality of the specifically describedfeature.

FIG. 12 is a schematic illustration of an example magnetic resonanceimaging system 1200, in accordance with various embodiments. As shown inFIG. 12 , the imaging system 1200 includes an imaging system 1210 and acontrol system 1290. The imaging system 1210 includes a radio frequencytransmit system (RF-TX) 1240, a radio frequency receive system (RF-RX)1270, a tuning box 1212, and a signal conditioning box 1214. The controlsystem 1290 includes a software design radio (SDR) 1292 and a controland interface system 1294. In accordance with various embodiments, eachof the various components of the system 1200 are communicatively coupledto other components of the system 1200.

In accordance with various embodiments, the various arrows shown in FIG.12 illustrate the interconnections of the various components in thesystem 1200 and the workflow thereof. For example, a workflow can beginat a computer resides within the control and interface system 1294. Theexample workflow includes calculation of a digital waveforms that areneeded and in a particular order that they are needed to be applied.Then, the digital waveforms are sent to a SDR 1292, which generates ananalog waveform that is sent to the radio frequency transmit system1240, which includes a radio frequency amplifier and a transmit coil.This amplifies the waveform produced by the SDR 1292 and sends it outinto a target subject, e.g., a body, patient or phantom. The propertiesof this system are adjusted with the signal conditioning box 1214, whichturns the imaging system 1210 on and off with a blanking signal, and thetuning box 1212, which adjusts the frequency response of the system. Inaccordance with various embodiments, the tuning box 1212 is an optionalcomponent in the imaging system 1210.

Upon receiving the waveform, the radio frequency transmit system 1240causes the spins in the target subject to generate a signal, which isdetected by the radio frequency receive system 1270. This radiofrequency receive system 1270 is also activated and manipulated with ablanking and tuning signal. Like the transmit system 1240, the receivesystem 1270 does not necessarily require the tuning signal. Onceactivated and after receiving a signal, the receive system 1270 sendsthe signal to the imaging system 1210, where it is digitized.

As shown in FIG. 12 , the signal conditioning box is configured to setcontrol signals sent to the various components of the system 1200 tovalues that those components will accept. In accordance with variousembodiments, in order to activate an RF amplifier, it requires a highvoltage signal that is higher than the SDR 1292 can produce. In suchinstances, the SDR 1292 can be configured to send a signal to the signalconditioning box 1214, which then amplifies it to a level that the RFamplifier will recognize.

It should be understood that any use of subheadings herein are fororganizational purposes, and should not be read to limit the applicationof those subheaded features to the various embodiments herein. Each andevery feature described herein is applicable and usable in all thevarious embodiments discussed herein and that all features describedherein can be used in any contemplated combination, regardless of thespecific example embodiments that are described herein. It shouldfurther be noted that exemplary description of specific features areused, largely for informational purposes, and not in any way to limitthe design, subfeature, and functionality of the specifically describedfeature.

FIG. 13 is a schematic illustration of an example magnetic resonanceimaging system 1300, in accordance with various embodiments. As shown inFIG. 13 , the imaging system 1300 includes an imaging system 1310 and acontrol system 1390. The imaging system 1310 includes a radio frequencytransmit system 1340, a tuning box 1312, and a signal conditioning box1314. The control system 1390 includes a SDR 1392 and a control andinterface system 1394. As shown in FIG. 13 , the radio frequencytransmit system 1340 includes a radio frequency power amplifier 1342, aradio frequency combiner 1344, a transformer (such as, a balun) 1346,and a radio frequency transmit coil 1348. In accordance with variousembodiments, each of the various components of the system 1300 arecommunicatively coupled to other components of the system 1300.

In accordance with various embodiments, the various arrows shown in FIG.13 illustrate the interconnections of the various components in thesystem 1300 and the workflow thereof. For example, a workflow can beginat a computer resides within the control and interface system 1394. Theexample workflow includes when an analog waveform is generated in theSDR 1392 and sent to the radio frequency power amplifier 1342. Thewaveform generated can be a chirped waveform, in accordance with variousembodiments. A control signal is also sent to the amplifier 1342 to bothturn it on and also to enable it only when the SDR 1392 is sending out atransmission (transmit) pulse. This waveform is amplified and sent tothe radio frequency combiner 1344, which splits the wave into two waves90 degrees out of phase, in accordance with various embodiments. Inaccordance with various embodiments, the wave is not split into twowaves 90 degrees out of phase, but can be instead sent directly to asingle port of the transmit coil 1348. These waves are sent to two portsof the transmit coil 1348, which then produces an RF pulse thatgenerates a signal that is detected by a receive system, such as receivesystems 1170 or 1270. In accordance with various embodiments, the wavesare sent to the transmit coil 1348 via the transformer 1346. Inaccordance with various embodiments, the system is controlled by thetuning box 1312, which alters the frequency response of the transmitcoil 1348 and the signal conditioning box 1314, which enables anddisables the amplifier 1342. In accordance with various embodiments, thetuning box 1312 and the transformers or baluns 1346 are optionalcomponents in imaging the imaging system 1310.

It should be understood that any use of subheadings herein are fororganizational purposes, and should not be read to limit the applicationof those subheaded features to the various embodiments herein. Each andevery feature described herein is applicable and usable in all thevarious embodiments discussed herein and that all features describedherein can be used in any contemplated combination, regardless of thespecific example embodiments that are described herein. It shouldfurther be noted that exemplary description of specific features areused, largely for informational purposes, and not in any way to limitthe design, subfeature, and functionality of the specifically describedfeature.

FIG. 14 is a schematic illustration of an example imaging system 1400,in accordance with various embodiments. As shown in FIG. 14 , theimaging system 1400 includes an imaging system 1410 and a control system1490. The control system 1490 includes a control and interface system1494. The imaging system 1410 includes a radio frequency receive system1470, and a tuning box 1412. As shown in FIG. 14 , the radio frequencyreceive system 1470 includes a radio frequency receive coil 1472, afirst stage preamplifier 1474, a transformer (such as, a balun) 1476,and a second stage preamplifier 1478. In accordance with variousembodiments, each of the various components of the system 1400 arecommunicatively coupled to other components of the system 1400.

In accordance with various embodiments, the various arrows shown in FIG.14 illustrate the interconnections of the various components in thesystem 1400 and the workflow thereof. For example, a workflow can beginat a computer resides within the control and interface system 1494. Theexample workflow includes when radio frequency signals generated by thetarget subject are detected at the receive system 1470. These signalsare induced by an transmit system, such as transmit systems 1140, 1240,or 1340. In accordance with various embodiments, the tuning box 1412 isconfigured to set the frequencies that the receive coil 1472 issensitive to. Upon detecting or receiving the signals at the receivecoil 1472 at the frequencies that the receive coil 1472 is tuned to,their signals are sent to the first stage preamplifier 1474, whichamplifies the received signals. In accordance with various embodiments,the system 1400 becomes less vulnerable to noise by amplification viathe first stage preamplifier 1474. The amplified signal is then sentthrough the transformer 1476 and into another stage of amplification atthe second stage preamplifier 1478, to further improve the signal'sresistance to noise. From the second stage, the now fully amplifiedsignal is sent to the control and interface system 1494, where it isdigitized and processed. The amount of coils may vary depending on theapplication.

It should be understood that any use of subheadings herein are fororganizational purposes, and should not be read to limit the applicationof those subheaded features to the various embodiments herein. Each andevery feature described herein is applicable and usable in all thevarious embodiments discussed herein and that all features describedherein can be used in any contemplated combination, regardless of thespecific example embodiments that are described herein. It shouldfurther be noted that exemplary description of specific features areused, largely for informational purposes, and not in any way to limitthe design, subfeature, and functionality of the specifically describedfeature.

Workflow Embodiments

In accordance with various embodiments, the various systems, and variouscombinations of features that make up the various system components andembodiments of the disclosed magnetic resonance imaging system aredisclosed herein.

FIG. 15 is a flowchart for a method S100 for performing magneticresonance imaging, according to various embodiments. The method S100includes at step S110 providing a magnetic resonance imaging system. Thesystem includes a radio frequency receive system comprising a radiofrequency receive coil, and a housing, wherein the housing includes apermanent magnet for providing an inhomogeneous permanent gradientfield, a radio frequency transmit system, and a single-sided gradientcoil set.

As shown in FIG. 15 , the method S100 includes placing the receive coilproximate a target subject, at step S120. The method S100 includesapplying a sequence of chirped pulses via the transmit system, at stepS130.

As shown in FIG. 15 , the method S100 includes applying a multi-sliceexcitation along the inhomogeneous permanent gradient field, at stepS140. The method S100 includes applying a plurality of gradient pulsesvia the gradient coil set orthogonal to the inhomogeneous permanentgradient field, at step S150.

As shown in FIG. 15 , the method S100 includes acquiring a signal of thetarget subject via the receive system, wherein the signal comprises atleast two chirped pulses, at step S160. The method S100 includes forminga magnetic resonance image of the target subject, at step S170.

In accordance with various embodiments, application of the chirpedpulses, multi-slice excitation, and gradient pulses are timed so thateach magnetization refocuses at a time of acquisition of the signal atthe receive system. In accordance with various embodiments, the systemfurther includes a power source, wherein the power source is configuredto flow current through at least one of the radio frequency transmitcoil, and the single-sided gradient coil set, to generate anelectromagnetic field in a region of interest, wherein the region ofinterest encompasses the target subject. In accordance with variousembodiments, the region of interest has a diameter of 4 to 12 inches.

In accordance with various embodiments, the multi-slice excitationincludes exciting multiple slices along an axis of the inhomogeneouspermanent gradient field, wherein each of the multiple slices has abandwidth that is similar to the broad bandwidth of the chirped pulses.In accordance with various embodiments, the chirped pulses compriseidentical bandwidths and differing durations. In accordance with variousembodiments, the chirped pulses have a bandwidth ranging from 1 kHz to10 kHz, 10 kHz to 40 kHz, 40 kHz to 100 kHz, 100 kHz to 400 kHz, 400 kHzto 1 MHz, or any ranges of bandwidth thereof.

In accordance with various embodiments, the chirped pulses areconfigured to produce a 1-dimensional signal along an axis of theinhomogeneous permanent gradient field. In accordance with variousembodiments, the 1-dimensional signal is the first 1-dimensional signal,the gradient pulses are configured to produce a second 1-dimensionalsignal and a third 1-dimensional signal that are orthogonal to eachother and to the axis of the inhomogeneous permanent gradient field.

In accordance with various embodiments, the gradient pulses areconfigured for encoding spatial information to the signal. In accordancewith various embodiments, the combination of the inhomogeneous permanentgradient field and the chirped pulses are configured for slice selectionin the inhomogeneous permanent gradient and a frequency encodinggradient.

In accordance with various embodiments, the target subject is ananatomical portion of a body. In accordance with various embodiments,the receive coil comprises an array of receive coils and each of thearray of receive coils is configured for specific anatomical portion ofthe body.

In accordance with various embodiments, the chirped pulses induce asignal in the target subject, and the signal is received by the receivecoil. In accordance with various embodiments, each of the at least twochirped pulses are split into two components that are 90 degrees out ofphase. In accordance with various embodiments, each of the at least twochirped pulses are split into two components that are sent to twoseparate ports of the transmit system.

In accordance with various embodiments, the magnetic resonance imagingsystem further comprises a signal conditioning box and a control system,wherein the signal conditioning box is configured to turn the controlsystem on and off with a blanking signal. In accordance with variousembodiments, turning the system on and off with the blanking signalrespectively enables and disables a radio frequency amplifier.

In accordance with various embodiments, the radio frequency transmitsystem comprises a transmit coil that is non-planar and oriented topartially surround the region of interest. In accordance with variousembodiments, the magnetic resonance imaging system further comprises atuning box, wherein the tuning box is configured to alter frequencyresponse of the transmit coil.

In accordance with various embodiments, the gradient coil set isnon-planar and oriented to partially surround the region of interest,and wherein the gradient coil set is configured to project a magneticfield gradient to the region of interest. In accordance with variousembodiments, the receive coil is a flexible coil configured to beaffixed to an anatomical portion of a patient for imaging within theregion of interest. In accordance with various embodiments, the receivecoil is in one of a single-loop coil configuration, figure-8 coilconfiguration, or butterfly coil configuration, wherein the receive coilis smaller than the region of interest.

In accordance with various embodiments, the transmit coil and thegradient coil set are concentric about the region of interest.

FIG. 16 is a flowchart for a method S200 for performing magneticresonance imaging, according to various embodiments. The method S200includes at step S210 providing an imaging system. The system includes aradio frequency receive coil, and a permanent magnet for providing apermanent gradient field.

As shown in FIG. 16 , the method S200 includes placing the receive coilproximate a target subject, at step S220. The method S200 includesapplying a sequence of chirped pulses having a wide bandwidth, at stepS230.

As shown in FIG. 16 , the method S200 includes applying a multi-sliceexcitation along the permanent gradient field, wherein the multi-sliceexcitation includes exciting multiple slices along an axis of thepermanent gradient field, wherein each of the multiple slices has abandwidth that is similar to the wide bandwidth of the chirped pulses,at step S240.

As shown in FIG. 16 , the method S200 includes applying a phase encodingfield along two orthogonal directions perpendicular to the axis of thepermanent gradient field, at step S250. The method S200 includesacquiring a magnetic resonance image of the target subject, at stepS260.

In accordance with various embodiments, application of the chirpedpulses, multi-slice excitation, and gradient pulses are timed so thateach magnetization refocuses at a time of acquisition of the signal. Inaccordance with various embodiments, each magnetization focuses in aregion of interest, wherein the region of interest encompasses thetarget subject. In accordance with various embodiments, the region ofinterest has a diameter of 4 to 12 inches.

In accordance with various embodiments, the chirped pulses compriseidentical bandwidths and differing durations. In accordance with variousembodiments, the chirped pulses have a bandwidth ranging from 1 kHz to10 kHz, 10 kHz to 40 kHz, 40 kHz to 100 kHz, 100 kHz to 400 kHz, 400 kHzto 1 MHz, or any ranges of bandwidth thereof.

In accordance with various embodiments, the chirped pulses areconfigured to produce a 1-dimensional signal along an axis of thepermanent gradient field. In accordance with various embodiments, the1-dimensional signal is the first 1-dimensional signal, the gradientpulses are configured to produce a second 1-dimensional signal and athird 1-dimensional signal that are orthogonal to each other and to theaxis of the permanent gradient field.

In accordance with various embodiments, the gradient pulses areconfigured for encoding spatial information to the signal. In accordancewith various embodiments, the combination of the permanent gradientfield and the chirped pulses are configured for slice selection in thepermanent gradient and a frequency encoding gradient.

In accordance with various embodiments, the target subject is ananatomical portion of a body.

In accordance with various embodiments, the receive coil comprises anarray of receive coils and each of the array of receive coils isconfigured for specific anatomical portion of the body. In accordancewith various embodiments, the chirped pulses induce a signal in thetarget subject, and the signal is received by the receive coil.

In accordance with various embodiments, the magnetic resonance imagingsystem further comprises a signal conditioning box and a control system,wherein the signal conditioning box is configured to turn the controlsystem on and off with a blanking signal. In accordance with variousembodiments, turning the system on and off with the blanking signalrespectively enables and disables a radio frequency amplifier.

In accordance with various embodiments, the imaging system furtherincludes a tuning box and a radio frequency transmit coil, wherein thetuning box is configured to alter frequency response of the transmitcoil. In accordance with various embodiments, the transmit coil isnon-planar and oriented to partially surround the region of interest.

In accordance with various embodiments, the imaging system furthercomprises a single-sided gradient coil set, wherein the gradient coilset is non-planar and oriented to partially surround the region ofinterest, and wherein the gradient coil set is configured to project amagnetic field gradient to the region of interest.

In accordance with various embodiments, the receive coil is a flexiblecoil configured to be affixed to an anatomical portion of a patient forimaging within the region of interest. In accordance with variousembodiments, the receive coil is in one of a single-loop coilconfiguration, figure-8 coil configuration, or butterfly coilconfiguration, wherein the receive coil is smaller than the region ofinterest.

FIG. 17 is a flowchart for a method S300 for performing magneticresonance imaging, according to various embodiments. The method S300includes at step S310 providing a permanent gradient magnetic field.

As shown in FIG. 17 , the method S300 includes placing a receive coilproximate a target subject, at step S320. The method S300 includesapplying a sequence of chirped pulses having a wide bandwidth, at stepS330. The method S300 includes selecting a slice selection gradienthaving the same wide bandwidth, at step S340.

As shown in FIG. 17 , the method S300 includes applying a multi-sliceexcitation technique along an axis of the permanent gradient magneticfield, at step S350. The method S300 includes applying a plurality ofgradient pulses orthogonal to the permanent gradient magnetic field, atstep S360. The method S300 includes acquiring a signal of the targetsubject via the receive coil, at step S370. The method S300 includesforming a magnetic resonance image of the target subject, at step S380.

In accordance with various embodiments, application of the chirpedpulses, multi-slice excitation technique, and gradient pulses are timedso that each magnetization refocuses at a time of acquisition of thesignal. In accordance with various embodiments, each magnetizationfocuses in a region of interest, wherein the region of interestencompasses the target subject. In accordance with various embodiments,the region of interest has a diameter of 4 to 12 inches.

In accordance with various embodiments, the chirped pulses compriseidentical bandwidths and differing durations. In accordance with variousembodiments, the chirped pulses have a bandwidth ranging from 1 kHz to10 kHz, 10 kHz to 40 kHz, 40 kHz to 100 kHz, 100 kHz to 400 kHz, 400 kHzto 1 MHz, or any ranges of bandwidth thereof.

In accordance with various embodiments, the chirped pulses areconfigured to produce a 1-dimensional signal along an axis of thepermanent gradient field. In accordance with various embodiments, the1-dimensional signal is the first 1-dimensional signal, the gradientpulses are configured to produce a second 1-dimensional signal and athird 1-dimensional signal that are orthogonal to each other and to theaxis of the permanent gradient field.

In accordance with various embodiments, the gradient pulses areconfigured for encoding spatial information to the signal. In accordancewith various embodiments, the combination of the permanent gradientfield and the chirped pulses are configured for slice selection in thepermanent gradient and a frequency encoding gradient.

In accordance with various embodiments, the target subject is ananatomical portion of a body.

In accordance with various embodiments, the receive coil comprises anarray of receive coils and each of the array of receive coils isconfigured for specific anatomical portion of the body. In accordancewith various embodiments, the chirped pulses induce a signal in thetarget subject, and the signal is received by the receive coil.

In accordance with various embodiments, the magnetic resonance imagingsystem further comprises a signal conditioning box and a control system,wherein the signal conditioning box is configured to turn the controlsystem on and off with a blanking signal. In accordance with variousembodiments, turning the system on and off with the blanking signalrespectively enables and disables a radio frequency amplifier.

In accordance with various embodiments, the imaging system furthercomprises a tuning box and a radio frequency transmit coil, wherein thetuning box is configured to alter frequency response of the transmitcoil. In accordance with various embodiments, the transmit coil isnon-planar and oriented to partially surround the region of interest.

In accordance with various embodiments, the imaging system furthercomprises a single-sided gradient coil set, wherein the gradient coilset is non-planar and oriented to partially surround the region ofinterest, and wherein the gradient coil set is configured to project amagnetic field gradient to the region of interest.

In accordance with various embodiments, the receive coil is a flexiblecoil configured to be affixed to an anatomical portion of a patient forimaging within the region of interest. In accordance with variousembodiments, the receive coil is in one of a single-loop coilconfiguration, figure-8 coil configuration, or butterfly coilconfiguration, wherein the receive coil is smaller than the region ofinterest.

Computer-Implemented System

FIG. 18 is a block diagram that illustrates a computer system 1800, inaccordance with various embodiments. In accordance with variousembodiments, the methods S100, S200, and S300 for performing magneticresonance imaging can be implemented via computer software or hardware.In accordance with various embodiments, the control systems, such ascontrol systems 1190, 1290, 1390, and 1490, or the control and interfacesystems, such as systems 1294, 1394, and 1494 can be communicativelyconnected to the computer system 1800 via a network connection that canbe either a “hardwired” physical network connection (e.g., Internet,LAN, WAN, VPN, etc.) or a wireless network connection (e.g., Wi-Fi,WLAN, etc.). In various embodiments, the computer system 1800 can be aworkstation, mainframe computer, distributed computing node (part of a“cloud computing” or distributed networking system), personal computer,mobile device, etc.

In accordance with various embodiments, the computer system 1800 caninclude a bus 1802 or other communication mechanism for communicatinginformation, and a processor 1804 coupled with bus 1802 for processinginformation. In various embodiments, computer system 1800 can alsoinclude a memory, which can be a random access memory (RAM) 1806 orother dynamic storage device, coupled to bus 1802 for determininginstructions to be executed by processor 1804. Memory also can be usedfor storing temporary variables or other intermediate information duringexecution of instructions to be executed by processor 1804. In variousembodiments, computer system 1800 can further include a read only memory(ROM) 1808 or other static storage device coupled to bus 1802 forstoring static information and instructions for processor 1804. Astorage device 1810, such as a magnetic disk or optical disk, can beprovided and coupled to bus 1802 for storing information andinstructions.

In various embodiments, computer system 1800 can be coupled via bus 1802to a display 1812, such as a cathode ray tube (CRT) or liquid crystaldisplay (LCD), for displaying information to a computer user. An inputdevice 1814, including alphanumeric and other keys, can be coupled tobus 1802 for communicating information and command selections toprocessor 1804. Another type of user input device is a cursor control1816, such as a mouse, a trackball or cursor direction keys forcommunicating direction information and command selections to processor1804 and for controlling cursor movement on display 1812. This inputdevice 1814 typically has two degrees of freedom in two axes, a firstaxis (i.e., x) and a second axis (i.e., y), that allows the device tospecify positions in a plane. However, it should be understood thatinput devices 1814 allowing for 3 dimensional (x, y and z) cursormovement are also contemplated herein.

Consistent with certain implementations of the present teachings,results can be provided by computer system 1800 in response to processor1804 executing one or more sequences of one or more instructionscontained in memory 1806. Such instructions can be read into memory 1806from another computer-readable medium or computer-readable storagemedium, such as storage device 1810. Execution of the sequences ofinstructions contained in memory 1806 can cause processor 1804 toperform the processes described herein. Alternatively hard-wiredcircuitry can be used in place of or in combination with softwareinstructions to implement the present teachings. Thus, implementationsof the present teachings are not limited to any specific combination ofhardware circuitry and software.

The term “computer-readable medium” (e.g., data store, data storage,etc.) or “computer-readable storage medium” as used herein refers to anymedia that participates in providing instructions to processor 1804 forexecution. Such a medium can take many forms, including but not limitedto, non-volatile media, volatile media, and transmission media. Examplesof non-volatile media can include, but are not limited to, optical,solid state, magnetic disks, such as storage device 1810. Examples ofvolatile media can include, but are not limited to, dynamic memory, suchas memory 1806. Examples of transmission media can include, but are notlimited to, coaxial cables, copper wire, and fiber optics, including thewires that comprise bus 1802.

Common forms of computer-readable media include, for example, a floppydisk, a flexible disk, hard disk, magnetic tape, or any other magneticmedium, a CD-ROM, any other optical medium, punch cards, paper tape, anyother physical medium with patterns of holes, a RAM, PROM, and EPROM, aFLASH-EPROM, any other memory chip or cartridge, or any other tangiblemedium from which a computer can read.

In addition to computer readable medium, instructions or data can beprovided as signals on transmission media included in a communicationsapparatus or system to provide sequences of one or more instructions toprocessor 1804 of computer system 1800 for execution. For example, acommunication apparatus may include a transceiver having signalsindicative of instructions and data. The instructions and data areconfigured to cause one or more processors to implement the functionsoutlined in the disclosure herein. Representative examples of datacommunications transmission connections can include, but are not limitedto, telephone modem connections, wide area networks (WAN), local areanetworks (LAN), infrared data connections, NFC connections, etc.

It should be appreciated that the methodologies described herein flowcharts, diagrams and accompanying disclosure can be implemented usingcomputer system 1800 as a standalone device or on a distributed networkof shared computer processing resources such as a cloud computingnetwork.

The methodologies described herein may be implemented by various meansdepending upon the application. For example, these methodologies may beimplemented in hardware, firmware, software, or any combination thereof.For a hardware implementation, the processing unit may be implementedwithin one or more application specific integrated circuits (ASICs),digital signal processors (DSPs), digital signal processing devices(DSPDs), programmable logic devices (PLDs), field programmable gatearrays (FPGAs), processors, controllers, micro-controllers,microprocessors, electronic devices, other electronic units designed toperform the functions described herein, or a combination thereof.

In various embodiments, the methods of the present teachings may beimplemented as firmware and/or a software program and applicationswritten in conventional programming languages such as C, C++, Python,etc. If implemented as firmware and/or software, the embodimentsdescribed herein can be implemented on a non-transitorycomputer-readable medium in which a program is stored for causing acomputer to perform the methods described above. It should be understoodthat the various engines described herein can be provided on a computersystem, such as computer system 1800, whereby processor 1804 wouldexecute the analyses and determinations provided by these engines,subject to instructions provided by any one of, or a combination of,memory components 1806/1808/1810 and user input provided via inputdevice 1814.

In accordance with various embodiments, a non-transitorycomputer-readable medium in which a program is stored for causing acomputer to perform a method for performing magnetic resonance imagingis provided. In accordance with various embodiments, the method includesproviding a magnetic resonance imaging system. In accordance withvarious embodiments, the system includes a radio frequency receivesystem comprising a radio frequency receive coil, and a housing. Inaccordance with various embodiments, the housing includes a permanentmagnet for providing an inhomogeneous permanent gradient field, a radiofrequency transmit system, and a single-sided gradient coil set. Inaccordance with various embodiments, the method further includes placingthe receive coil proximate a target subject; applying a sequence ofchirped pulses via the transmit system; applying a multi-sliceexcitation along the inhomogeneous permanent gradient field; applying aplurality of gradient pulses via the gradient coil set orthogonal to theinhomogeneous permanent gradient field; acquiring a signal of the targetsubject via the receive system, wherein the signal comprises at leasttwo chirped pulses; and forming a magnetic resonance image of the targetsubject.

In accordance with various embodiments, application of the chirpedpulses, multi-slice excitation, and gradient pulses are timed so thateach magnetization refocuses at a time of acquisition of the signal atthe receive system. In accordance with various embodiments, the systemfurther includes a power source, wherein the power source is configuredto flow current through at least one of the radio frequency transmitsystem, and the single-sided gradient coil set, to generate anelectromagnetic field in a region of interest, wherein the region ofinterest encompasses the target subject. In accordance with variousembodiments, the region of interest has a diameter of 4 to 12 inches.

In accordance with various embodiments, the multi-slice excitationincludes exciting multiple slices along an axis of the inhomogeneouspermanent gradient field, wherein each of the multiple slices has abandwidth that is similar to the broad bandwidth of the chirped pulses.In accordance with various embodiments, the chirped pulses compriseidentical bandwidths and differing durations. In accordance with variousembodiments, the chirped pulses have a bandwidth ranging from 1 kHz to10 kHz, 10 kHz to 40 kHz, 40 kHz to 100 kHz, 100 kHz to 400 kHz, 400 kHzto 1 MHz, or any ranges of bandwidth thereof.

In accordance with various embodiments, the chirped pulses areconfigured to produce a 1-dimensional signal along an axis of theinhomogeneous permanent gradient field. In accordance with variousembodiments, the 1-dimensional signal is the first 1-dimensional signal,the gradient pulses are configured to produce a second 1-dimensionalsignal and a third 1-dimensional signal that are orthogonal to eachother and to the axis of the inhomogeneous permanent gradient field.

In accordance with various embodiments, the gradient pulses areconfigured for encoding spatial information to the signal. In accordancewith various embodiments, the combination of the inhomogeneous permanentgradient field and the chirped pulses are configured for slice selectionin the inhomogeneous permanent gradient and a frequency encodinggradient. In accordance with various embodiments, the target subject isan anatomical portion of a body.

In accordance with various embodiments, the receive coil includes anarray of receive coils and each of the array of receive coils isconfigured for specific anatomical portion of a body. In accordance withvarious embodiments, the chirped pulses induce a signal in the targetsubject, and the signal is received by the receive coil. In accordancewith various embodiments, each of the at least two chirped pulses aresplit into two components that are 90 degrees out of phase. Inaccordance with various embodiments, each of the at least two chirpedpulses are split into two components that are sent to two separate portsof the transmit system.

In accordance with various embodiments, the magnetic resonance imagingsystem further includes a signal conditioning box and a control system,wherein the signal conditioning box is configured to turn the controlsystem on and off with a blanking signal. In accordance with variousembodiments, turning the control system on and off with the blankingsignal respectively enables and disables a radio frequency amplifier.

In accordance with various embodiments, the radio frequency transmitsystem includes a transmit coil that is non-planar and oriented topartially surround the region of interest. In accordance with variousembodiments, the magnetic resonance imaging system further includes atuning box, wherein the tuning box is configured to alter the frequencyresponse of the transmit coil. In accordance with various embodiments,the gradient coil set is non-planar and oriented to partially surroundthe region of interest, and wherein the gradient coil set is configuredto project a magnetic field gradient to the region of interest.

In accordance with various embodiments, the receive coil is a flexiblecoil configured to be affixed to an anatomical portion of a patient forimaging within the region of interest. In accordance with variousembodiments, the receive coil is in one of a single-loop coilconfiguration, figure-8 coil configuration, or butterfly coilconfiguration, wherein the receive coil is smaller than the region ofinterest. In accordance with various embodiments, the transmit coil andthe gradient coil set are concentric about the region of interest.

In accordance with various embodiments, a non-transitorycomputer-readable medium in which a program is stored for causing acomputer to perform a method for performing magnetic resonance imagingis provided. In accordance with various embodiments, the method includesproviding an imaging system comprising a radio frequency receive coil,and a permanent magnet for providing a permanent gradient field. Inaccordance with various embodiments, the method further includes placingthe receive coil proximate a target subject; applying a sequence ofchirped pulses having a wide bandwidth; applying a multi-sliceexcitation along the permanent gradient field, wherein the multi-sliceexcitation includes exciting multiple slices along an axis of thepermanent gradient field, wherein each of the multiple slices has abandwidth that is similar to the wide bandwidth of the chirped pulses;applying a phase encoding field along two orthogonal directionsperpendicular to the axis of the permanent gradient field; and acquiringa magnetic resonance image of the target subject.

In accordance with various embodiments, application of the chirpedpulses, multi-slice excitation, and gradient pulses are timed so thateach magnetization refocuses at a time of acquisition of a signal. Inaccordance with various embodiments, each magnetization focuses in aregion of interest, wherein the region of interest encompasses thetarget subject. In accordance with various embodiments, the region ofinterest has a diameter of 4 to 12 inches.

In accordance with various embodiments, the chirped pulses compriseidentical bandwidths and differing durations. In accordance with variousembodiments, the chirped pulses have a bandwidth ranging from 1 kHz to10 kHz, 10 kHz to 40 kHz, 40 kHz to 100 kHz, 100 kHz to 400 kHz, 400 kHzto 1 MHz, or any ranges of bandwidth thereof.

In accordance with various embodiments, the chirped pulses areconfigured to produce a 1-dimensional signal along an axis of thepermanent gradient field. In accordance with various embodiments, themethod further includes applying a plurality of gradient pulses via agradient coil set orthogonal to the inhomogeneous permanent gradientfield, wherein the 1-dimensional signal is the first 1-dimensionalsignal, the gradient pulses are configured to produce a second1-dimensional signal and a third 1-dimensional signal that areorthogonal to each other and to the axis of the permanent gradientfield.

In accordance with various embodiments, the method further includesapplying a plurality of gradient pulses via a gradient coil setorthogonal to the inhomogeneous permanent gradient field, wherein thegradient pulses are configured for encoding spatial information to thesignal. In accordance with various embodiments, the combination of thepermanent gradient field and the chirped pulses are configured for sliceselection in the permanent gradient and a frequency encoding gradient.In accordance with various embodiments, the target subject is ananatomical portion of a body.

In accordance with various embodiments, the receive coil includes anarray of receive coils and each of the array of receive coils isconfigured for a specific anatomical portion of a body. In accordancewith various embodiments, the chirped pulses induce a signal in thetarget subject, and the signal is received by the receive coil.

In accordance with various embodiments, the magnetic resonance imagingsystem further includes a signal conditioning box and a control system,wherein the signal conditioning box is configured to turn the controlsystem on and off with a blanking signal. In accordance with variousembodiments, turning the system on and off with the blanking signalrespectively enables and disables a radio frequency amplifier.

In accordance with various embodiments, the imaging system furtherincludes a tuning box and a radio frequency transmit coil, wherein thetuning box is configured to alter the frequency response of the transmitcoil. In accordance with various embodiments, the transmit coil isnon-planar and oriented to partially surround the region of interest.

In accordance with various embodiments, the imaging system furtherincludes a single-sided gradient coil set, wherein the gradient coil setis non-planar and oriented to partially surround the region of interest,and wherein the gradient coil set is configured to project a magneticfield gradient to the region of interest.

In accordance with various embodiments, the receive coil is a flexiblecoil configured to be affixed to an anatomical portion of a patient forimaging within the region of interest. In accordance with variousembodiments, the receive coil is in one of a single-loop coilconfiguration, figure-8 coil configuration, or butterfly coilconfiguration, wherein the receive coil is smaller than the region ofinterest.

In accordance with various embodiments, a non-transitorycomputer-readable medium in which a program is stored for causing acomputer to perform a method for performing magnetic resonance imagingis provided. In accordance with various embodiments, the method includesproviding a permanent gradient magnetic field; placing a receive coilproximate a target subject; applying a sequence of chirped pulses havinga wide bandwidth; selecting a slice selection gradient having the samewide bandwidth; applying a multi-slice excitation technique along anaxis of the permanent gradient magnetic field; applying a plurality ofgradient pulses orthogonal to the permanent gradient magnetic field;acquiring a signal of the target subject via the receive coil; andforming a magnetic resonance image of the target subject.

In accordance with various embodiments, application of the chirpedpulses, multi-slice excitation technique, and gradient pulses are timedso that each magnetization refocuses at a time of acquisition of thesignal. In accordance with various embodiments, each magnetizationfocuses in a region of interest, wherein the region of interestencompasses the target subject. In accordance with various embodiments,the region of interest has a diameter of 4 to 12 inches.

In accordance with various embodiments, the chirped pulses compriseidentical bandwidths and differing durations. In accordance with variousembodiments, the chirped pulses have a bandwidth ranging from 1 kHz to10 kHz, 10 kHz to 40 kHz, 40 kHz to 100 kHz, 100 kHz to 400 kHz, 400 kHzto 1 MHz, or any ranges of bandwidth thereof.

In accordance with various embodiments, the chirped pulses areconfigured to produce a 1-dimensional signal along an axis of thepermanent gradient field. In accordance with various embodiments, the1-dimensional signal is the first 1-dimensional signal, the gradientpulses are configured to produce a second 1-dimensional signal and athird 1-dimensional signal that are orthogonal to each other and to theaxis of the permanent gradient field.

In accordance with various embodiments, the gradient pulses areconfigured for encoding spatial information to the signal. In accordancewith various embodiments, the combination of the permanent gradientfield and the chirped pulses are configured for slice selection in thepermanent gradient and a frequency encoding gradient. In accordance withvarious embodiments, the target subject is an anatomical portion of abody.

In accordance with various embodiments, the receive coil comprises anarray of receive coils and each of the array of receive coils isconfigured for specific anatomical portion of a body. In accordance withvarious embodiments, the chirped pulses induce a signal in the targetsubject, and the signal is received by the receive coil.

In accordance with various embodiments, the magnetic resonance imagingsystem further includes a signal conditioning box and a control system,wherein the signal conditioning box is configured to turn the controlsystem on and off with a blanking signal. In accordance with variousembodiments, turning the system on and off with the blanking signalrespectively enables and disables a radio frequency amplifier.

In accordance with various embodiments, the imaging system furtherincludes a tuning box and a radio frequency transmit coil, wherein thetuning box is configured to alter frequency response of the transmitcoil. In accordance with various embodiments, the transmit coil isnon-planar and oriented to partially surround the region of interest.

In accordance with various embodiments, the imaging system furtherincludes a single-sided gradient coil set, wherein the gradient coil setis non-planar and oriented to partially surround the region of interest,and wherein the gradient coil set is configured to project a magneticfield gradient to the region of interest.

In accordance with various embodiments, the receive coil is a flexiblecoil configured to be affixed to an anatomical portion of a patient forimaging within the region of interest. In accordance with variousembodiments, the receive coil is in one of a single-loop coilconfiguration, figure-8 coil configuration, or butterfly coilconfiguration, wherein the receive coil is smaller than the region ofinterest.

Recitation of Embodiments

EMBODIMENT 1. A method for performing magnetic resonance imagingcomprising providing a magnetic resonance imaging system comprising aradio frequency receive system comprising a radio frequency receivecoil, and a housing, wherein the housing comprises a permanent magnetfor providing an inhomogeneous permanent gradient field, a radiofrequency transmit system, and a single-sided gradient coil set. Themethod further comprises placing the receive coil proximate a targetsubject; applying a sequence of chirped pulses via the transmit system;applying a multi-slice excitation along the inhomogeneous permanentgradient field; applying a plurality of gradient pulses via the gradientcoil set orthogonal to the inhomogeneous permanent gradient field;acquiring a signal of the target subject via the receive system, whereinthe signal comprises at least two chirped pulses; and forming a magneticresonance image of the target subject.

EMBODIMENT 2. The method of embodiment 1, wherein application of thechirped pulses, multi-slice excitation, and gradient pulses are timed sothat each magnetization refocuses at a time of acquisition of the signalat the receive system.

EMBODIMENT 3. The method of any preceding embodiment, further comprisinga power source, wherein the power source is configured to flow currentthrough at least one of the radio frequency transmit system, and thesingle-sided gradient coil set, to generate an electromagnetic field ina region of interest, wherein the region of interest encompasses thetarget subject.

EMBODIMENT 4. The method of embodiment 3, wherein the region of interesthas a diameter of 4 to 12 inches.

EMBODIMENT 5. The method of any preceding embodiment, wherein themulti-slice excitation includes exciting multiple slices along an axisof the inhomogeneous permanent gradient field, wherein each of themultiple slices has a bandwidth that is similar to the broad bandwidthof the chirped pulses.

EMBODIMENT 6. The method of any preceding embodiment, wherein thechirped pulses comprise identical bandwidths and differing durations.

EMBODIMENT 7. The method of any preceding embodiment, wherein thechirped pulses have a bandwidth ranging from 1 kHz to 10 kHz, 10 kHz to40 kHz, 40 kHz to 100 kHz, 100 kHz to 400 kHz, 400 kHz to 1 MHz, or anyranges of bandwidth thereof.

EMBODIMENT 8. The method of any preceding embodiment, wherein thechirped pulses are configured to produce a 1-dimensional signal along anaxis of the inhomogeneous permanent gradient field.

EMBODIMENT 9. The method of embodiment 8, wherein the 1-dimensionalsignal is the first 1-dimensional signal, the gradient pulses areconfigured to produce a second 1-dimensional signal and a third1-dimensional signal that are orthogonal to each other and to the axisof the inhomogeneous permanent gradient field.

EMBODIMENT 10. The method of any preceding embodiment, wherein thegradient pulses are configured for encoding spatial information to thesignal.

EMBODIMENT 11. The method of any preceding embodiment, wherein thecombination of the inhomogeneous permanent gradient field and thechirped pulses are configured for slice selection in the inhomogeneouspermanent gradient and a frequency encoding gradient.

EMBODIMENT 12. The method of any preceding embodiment, wherein thetarget subject is an anatomical portion of a body.

EMBODIMENT 13. The method of any preceding embodiment, wherein thereceive coil comprises an array of receive coils and each of the arrayof receive coils is configured for specific anatomical portion of abody.

EMBODIMENT 14. The method of any preceding embodiment, wherein thechirped pulses induce a signal in the target subject, and the signal isreceived by the receive coil.

EMBODIMENT 15. The method of any preceding embodiment, wherein each ofthe at least two chirped pulses are split into two components that are90 degrees out of phase.

EMBODIMENT 16. The method of any preceding embodiment, wherein each ofthe at least two chirped pulses are split into two components that aresent to two separate ports of the transmit system.

EMBODIMENT 17. The method of any preceding embodiment, wherein themagnetic resonance imaging system further comprises a signalconditioning box and a control system, wherein the signal conditioningbox is configured to turn the control system on and off with a blankingsignal.

EMBODIMENT 18. The method of embodiment 17, wherein turning the controlsystem on and off with the blanking signal respectively enables anddisables a radio frequency amplifier.

EMBODIMENT 19. The method of embodiment 3, wherein the radio frequencytransmit system comprises a transmit coil that is non-planar andoriented to partially surround the region of interest.

EMBODIMENT 20. The method of embodiment 19, wherein the magneticresonance imaging system further comprises a tuning box, wherein thetuning box is configured to alter the frequency response of the transmitcoil.

EMBODIMENT 21. The method of embodiment 3, wherein the gradient coil setis non-planar and oriented to partially surround the region of interest,and wherein the gradient coil set is configured to project a magneticfield gradient to the region of interest.

EMBODIMENT 22. The method of embodiment 3, wherein the receive coil is aflexible coil configured to be affixed to an anatomical portion of apatient for imaging within the region of interest.

EMBODIMENT 23. The method of embodiment 3, wherein the receive coil isin one of a single-loop coil configuration, figure-8 coil configuration,or butterfly coil configuration, wherein the receive coil is smallerthan the region of interest.

EMBODIMENT 24. The method of embodiment 19, wherein the transmit coiland the gradient coil set are concentric about the region of interest.

EMBODIMENT 25. A method for performing magnetic resonance imagingcomprising providing an imaging system comprising a radio frequencyreceive coil, and a permanent magnet for providing a permanent gradientfield. The method further comprises placing the receive coil proximate atarget subject; applying a sequence of chirped pulses having a widebandwidth; applying a multi-slice excitation along the permanentgradient field, wherein the multi-slice excitation includes excitingmultiple slices along an axis of the permanent gradient field, whereineach of the multiple slices has a bandwidth that is similar to the widebandwidth of the chirped pulses; applying a phase encoding field alongtwo orthogonal directions perpendicular to the axis of the permanentgradient field; and acquiring a magnetic resonance image of the targetsubject.

EMBODIMENT 26. The method of embodiment 25, wherein application of thechirped pulses, multi-slice excitation, and gradient pulses are timed sothat each magnetization refocuses at a time of acquisition of a signal.

EMBODIMENT 27. The method of embodiment 26, wherein each magnetizationfocuses in a region of interest, wherein the region of interestencompasses the target subject.

EMBODIMENT 28. The method of embodiment 27, wherein the region ofinterest has a diameter of 4 to 12 inches.

EMBODIMENT 29. The method of any of embodiments 25 to 28, wherein thechirped pulses comprise identical bandwidths and differing durations.

EMBODIMENT 30. The method of embodiment 29, wherein the chirped pulseshave a bandwidth ranging from 1 kHz to 10 kHz, 10 kHz to 40 kHz, 40 kHzto 100 kHz, 100 kHz to 400 kHz, 400 kHz to 1 MHz, or any ranges ofbandwidth thereof.

EMBODIMENT 31. The method of any of embodiments 25 to 30, wherein thechirped pulses are configured to produce a 1-dimensional signal along anaxis of the permanent gradient field.

EMBODIMENT 32. The method of embodiment 31, further comprising applyinga plurality of gradient pulses via a gradient coil set orthogonal to theinhomogeneous permanent gradient field, wherein the 1-dimensional signalis the first 1-dimensional signal, the gradient pulses are configured toproduce a second 1-dimensional signal and a third 1-dimensional signalthat are orthogonal to each other and to the axis of the permanentgradient field.

EMBODIMENT 33. The method of any of embodiments 25 to 32, furthercomprising applying a plurality of gradient pulses via a gradient coilset orthogonal to the inhomogeneous permanent gradient field, whereinthe gradient pulses are configured for encoding spatial information tothe signal.

EMBODIMENT 34. The method of any of embodiments 25 to 33, wherein thecombination of the permanent gradient field and the chirped pulses areconfigured for slice selection in the permanent gradient and a frequencyencoding gradient.

EMBODIMENT 35. The method of any of embodiments 25 to 34, wherein thetarget subject is an anatomical portion of a body.

EMBODIMENT 36. The method of any of embodiments 25 to 35, wherein thereceive coil comprises an array of receive coils and each of the arrayof receive coils is configured for a specific anatomical portion of abody.

EMBODIMENT 37. The method of any of embodiments 25 to 36, wherein thechirped pulses induce a signal in the target subject, and the signal isreceived by the receive coil.

EMBODIMENT 38. The method of any of embodiments 25 to 37, wherein themagnetic resonance imaging system further comprises a signalconditioning box and a control system, wherein the signal conditioningbox is configured to turn the control system on and off with a blankingsignal.

EMBODIMENT 39. The method of embodiment 38, wherein turning the systemon and off with the blanking signal respectively enables and disables aradio frequency amplifier.

EMBODIMENT 40. The method of embodiment 27, wherein the imaging systemfurther comprises a tuning box and a radio frequency transmit coil,wherein the tuning box is configured to alter the frequency response ofthe transmit coil.

EMBODIMENT 41. The method of embodiment 40, wherein the transmit coil isnon-planar and oriented to partially surround the region of interest.

EMBODIMENT 42. The method of embodiment 27, wherein the imaging systemfurther comprises a single-sided gradient coil set, wherein the gradientcoil set is non-planar and oriented to partially surround the region ofinterest, and wherein the gradient coil set is configured to project amagnetic field gradient to the region of interest.

EMBODIMENT 43. The method of embodiment 27, wherein the receive coil isa flexible coil configured to be affixed to an anatomical portion of apatient for imaging within the region of interest.

EMBODIMENT 44. The method of embodiment 27, wherein the receive coil isin one of a single-loop coil configuration, figure-8 coil configuration,or butterfly coil configuration, wherein the receive coil is smallerthan the region of interest.

EMBODIMENT 45. A method for performing magnetic resonance imagingcomprising providing a permanent gradient magnetic field; placing areceive coil proximate a target subject; applying a sequence of chirpedpulses having a wide bandwidth; selecting a slice selection gradienthaving the same wide bandwidth; applying a multi-slice excitationtechnique along an axis of the permanent gradient magnetic field;applying a plurality of gradient pulses orthogonal to the permanentgradient magnetic field; acquiring a signal of the target subject viathe receive coil; and forming a magnetic resonance image of the targetsubject.

EMBODIMENT 46. The method of embodiment 45, wherein application of thechirped pulses, multi-slice excitation technique, and gradient pulsesare timed so that each magnetization refocuses at a time of acquisitionof the signal.

EMBODIMENT 47. The method of embodiment 46, wherein each magnetizationfocuses in a region of interest, wherein the region of interestencompasses the target subject.

EMBODIMENT 48. The method of embodiment 47, wherein the region ofinterest has a diameter of 4 to 12 inches.

EMBODIMENT 49. The method of any of embodiments 45 to 48, wherein thechirped pulses comprise identical bandwidths and differing durations.

EMBODIMENT 50. The method of embodiment 49, wherein the chirped pulseshave a bandwidth ranging from 1 kHz to 10 kHz, 10 kHz to 40 kHz, 40 kHzto 100 kHz, 100 kHz to 400 kHz, 400 kHz to 1 MHz, or any ranges ofbandwidth thereof.

EMBODIMENT 51. The method of any of embodiments 45 to 50, wherein thechirped pulses are configured to produce a 1-dimensional signal along anaxis of the permanent gradient field.

EMBODIMENT 52. The method of embodiment 51, wherein the 1-dimensionalsignal is the first 1-dimensional signal, the gradient pulses areconfigured to produce a second 1-dimensional signal and a third1-dimensional signal that are orthogonal to each other and to the axisof the permanent gradient field.

EMBODIMENT 53. The method of any of embodiments 45 to 52, wherein thegradient pulses are configured for encoding spatial information to thesignal.

EMBODIMENT 54. The method of any of embodiments 45 to 53, wherein thecombination of the permanent gradient field and the chirped pulses areconfigured for slice selection in the permanent gradient and a frequencyencoding gradient.

EMBODIMENT 55. The method of any of embodiments 45 to 54, wherein thetarget subject is an anatomical portion of a body.

EMBODIMENT 56. The method of any of embodiments 45 to 55, wherein thereceive coil comprises an array of receive coils and each of the arrayof receive coils is configured for specific anatomical portion of abody.

EMBODIMENT 57. The method of any of embodiments 45 to 56, wherein thechirped pulses induce a signal in the target subject, and the signal isreceived by the receive coil.

EMBODIMENT 58. The method of any of embodiments 45 to 57, wherein themagnetic resonance imaging system further comprises a signalconditioning box and a control system, wherein the signal conditioningbox is configured to turn the control system on and off with a blankingsignal.

EMBODIMENT 59. The method of embodiment 58, wherein turning the systemon and off with the blanking signal respectively enables and disables aradio frequency amplifier.

EMBODIMENT 60. The method of embodiment 47, wherein the imaging systemfurther comprises a tuning box and a radio frequency transmit coil,wherein the tuning box is configured to alter frequency response of thetransmit coil.

EMBODIMENT 61. The method of embodiment 60, wherein the transmit coil isnon-planar and oriented to partially surround the region of interest.

EMBODIMENT 62. The method of embodiment 47, wherein the imaging systemfurther comprises a single-sided gradient coil set, wherein the gradientcoil set is non-planar and oriented to partially surround the region ofinterest, and wherein the gradient coil set is configured to project amagnetic field gradient to the region of interest.

EMBODIMENT 63. The method of embodiment 47, wherein the receive coil isa flexible coil configured to be affixed to an anatomical portion of apatient for imaging within the region of interest.

EMBODIMENT 64. The method of embodiment 47, wherein the receive coil isin one of a single-loop coil configuration, figure-8 coil configuration,or butterfly coil configuration, wherein the receive coil is smallerthan the region of interest.

EMBODIMENT 65. A magnetic resonance imaging system comprising a radiofrequency receive system comprising a radio frequency receive coilconfigured to be placed proximate a target subject, wherein the receivesystem is configured to deliver a signal of a target subject for forminga magnetic resonance image of the target subject, wherein the signalcomprises at least two chirped pulses, and a housing, wherein thehousing comprises a permanent magnet for providing an inhomogeneouspermanent gradient field, wherein the imaging system is configured toapply a multi-slice excitation along the inhomogeneous permanentgradient field, a radio frequency transmit system configured to delivera sequence of chirped pulses, and a single-sided gradient coil setconfigured to deliver a plurality of gradient pulses orthogonal to theinhomogeneous permanent gradient field.

EMBODIMENT 66. The system of embodiment 65, further comprising a powersource, wherein the power source is configured to flow current throughat least one of the radio frequency transmit system, and thesingle-sided gradient coil set, to generate an electromagnetic field ina region of interest, wherein the region of interest encompasses thetarget subject.

EMBODIMENT 67. The system of embodiment 66, wherein the region ofinterest has a diameter of 4 to 12 inches.

EMBODIMENT 68. The method of any of embodiments 65 to 67, wherein theimaging system is configured to apply a multi-slice excitationcomprising exciting multiple slices along an axis of the inhomogeneouspermanent gradient field, wherein each of the multiple slices has abandwidth that is similar to the broad bandwidth of the chirped pulses.

EMBODIMENT 69. The system of any of embodiments 65 to 68, wherein thechirped pulses comprise identical bandwidths and differing durations.

EMBODIMENT 70. The system of any of embodiments 65 to 69, wherein thechirped pulses have a bandwidth ranging from 1 kHz to 10 kHz, 10 kHz to40 kHz, 40 kHz to 100 kHz, 100 kHz to 400 kHz, 400 kHz to 1 MHz, or anyranges of bandwidth thereof.

EMBODIMENT 71. The system of any of embodiments 65 to 70, wherein thechirped pulses are configured to produce a 1-dimensional signal along anaxis of the inhomogeneous permanent gradient field.

EMBODIMENT 72. The system of embodiment 71, wherein the 1-dimensionalsignal is the first 1-dimensional signal, and the gradient pulses areconfigured to produce a second 1-dimensional signal and a third1-dimensional signal that are orthogonal to each other and to the axisof the inhomogeneous permanent gradient field.

EMBODIMENT 73. The system of any of embodiments 65 to 72, wherein thegradient pulses are configured for encoding spatial information to thesignal.

EMBODIMENT 74. The system of any of embodiments 65 to 73, wherein thecombination of the inhomogeneous permanent gradient field and thechirped pulses are configured for slice selection in the inhomogeneouspermanent gradient and a frequency encoding gradient.

EMBODIMENT 75. The system of any of embodiments 65 to 74, wherein thetarget subject is an anatomical portion of a body.

EMBODIMENT 76. The system of any of embodiments 65 to 75, wherein thereceive coil comprises an array of receive coils and each of the arrayof receive coils is configured for specific anatomical portion of abody.

EMBODIMENT 77. The system of any of embodiments 65 to 76, wherein thechirped pulses induce a signal in the target subject, and the receivecoil is configured to receive the signal.

EMBODIMENT 78. The system of any of embodiments 65 to 77, wherein eachof the at least two chirped pulses are split into two components thatare 90 degrees out of phase.

EMBODIMENT 79. The system of any of embodiments 65 to 78, wherein thetransmit system further comprises two separate ports configured togenerate the at least two chirped pulses.

EMBODIMENT 80. The system of any of embodiments 65 to 79, wherein themagnetic resonance imaging system further comprises a signalconditioning box and a control system, wherein the signal conditioningbox is configured to turn the control system on and off with a blankingsignal.

EMBODIMENT 81. The system of embodiment 80, further comprising a radiofrequency amplifier, the amplifier enabled and disabled when the controlsystem is turned on and off with the blanking signal.

EMBODIMENT 82. The system of embodiment 66, wherein the radio frequencytransmit system comprises a transmit coil that is non-planar andoriented to partially surround the region of interest.

EMBODIMENT 83. The system of embodiment 82, wherein the magneticresonance imaging system further comprises a tuning box, wherein thetuning box is configured to alter the frequency response of the transmitcoil.

EMBODIMENT 84. The system of embodiment 66, wherein the gradient coilset is non-planar and oriented to partially surround the region ofinterest, and wherein the gradient coil set is configured to project amagnetic field gradient to the region of interest.

EMBODIMENT 85. The system of embodiment 66, wherein the receive coil isa flexible coil configured to be affixed to an anatomical portion of apatient for imaging within the region of interest.

EMBODIMENT 86. The system of embodiment 66, wherein the receive coil isin one of a single-loop coil configuration, figure-8 coil configuration,or butterfly coil configuration, wherein the receive coil is smallerthan the region of interest.

EMBODIMENT 87. The system of embodiment 82, wherein the transmit coiland the gradient coil set are concentric about the region of interest.

EMBODIMENT 88. A non-transitory computer-readable medium in which aprogram is stored for causing a computer to perform a method forperforming magnetic resonance imaging, the method comprising providing amagnetic resonance imaging system comprising a radio frequency receivesystem comprising a radio frequency receive coil, and a housing, whereinthe housing comprises a permanent magnet for providing an inhomogeneouspermanent gradient field, a radio frequency transmit system, and asingle-sided gradient coil set. The method further comprises placing thereceive coil proximate a target subject; applying a sequence of chirpedpulses via the transmit system; applying a multi-slice excitation alongthe inhomogeneous permanent gradient field; applying a plurality ofgradient pulses via the gradient coil set orthogonal to theinhomogeneous permanent gradient field; acquiring a signal of the targetsubject via the receive system, wherein the signal comprises at leasttwo chirped pulses; and forming a magnetic resonance image of the targetsubject.

EMBODIMENT 89. The method of embodiment 88, wherein application of thechirped pulses, multi-slice excitation, and gradient pulses are timed sothat each magnetization refocuses at a time of acquisition of the signalat the receive system.

EMBODIMENT 90. The method of any of embodiments 88 and 89, furthercomprising a power source, wherein the power source is configured toflow current through at least one of the radio frequency transmitsystem, and the single-sided gradient coil set, to generate anelectromagnetic field in a region of interest, wherein the region ofinterest encompasses the target subject.

EMBODIMENT 91. The method of embodiment 90, wherein the region ofinterest has a diameter of 4 to 12 inches.

EMBODIMENT 92. The method of any of embodiments 88 to 91, wherein themulti-slice excitation includes exciting multiple slices along an axisof the inhomogeneous permanent gradient field, wherein each of themultiple slices has a bandwidth that is similar to the broad bandwidthof the chirped pulses.

EMBODIMENT 93. The method of any of embodiments 88 to 92, wherein thechirped pulses comprise identical bandwidths and differing durations.

EMBODIMENT 94. The method of any of embodiments 88 to 93, wherein thechirped pulses have a bandwidth ranging from 1 kHz to 10 kHz, 10 kHz to40 kHz, 40 kHz to 100 kHz, 100 kHz to 400 kHz, 400 kHz to 1 MHz, or anyranges of bandwidth thereof.

EMBODIMENT 95. The method of any of embodiments 88 to 94, wherein thechirped pulses are configured to produce a 1-dimensional signal along anaxis of the inhomogeneous permanent gradient field.

EMBODIMENT 96. The method of embodiment 95, wherein the 1-dimensionalsignal is the first 1-dimensional signal, the gradient pulses areconfigured to produce a second 1-dimensional signal and a third1-dimensional signal that are orthogonal to each other and to the axisof the inhomogeneous permanent gradient field.

EMBODIMENT 97. The method of any of embodiments 88 to 96, wherein thegradient pulses are configured for encoding spatial information to thesignal.

EMBODIMENT 98. The method of any of embodiments 88 to 97, wherein thecombination of the inhomogeneous permanent gradient field and thechirped pulses are configured for slice selection in the inhomogeneouspermanent gradient and a frequency encoding gradient.

EMBODIMENT 99. The method of any of embodiments 88 to 98, wherein thetarget subject is an anatomical portion of a body.

EMBODIMENT 100. The method of any of embodiments 88 to 98, wherein thereceive coil comprises an array of receive coils and each of the arrayof receive coils is configured for specific anatomical portion of abody.

EMBODIMENT 101. The method of any of embodiments 88 to 100, wherein thechirped pulses induce a signal in the target subject, and the signal isreceived by the receive coil.

EMBODIMENT 102. The method of any of embodiments 88 to 101, wherein eachof the at least two chirped pulses are split into two components thatare 90 degrees out of phase.

EMBODIMENT 103. The method of any of embodiments 88 to 102, wherein eachof the at least two chirped pulses are split into two components thatare sent to two separate ports of the transmit system.

EMBODIMENT 104. The method of any of embodiments 88 to 103, wherein themagnetic resonance imaging system further comprises a signalconditioning box and a control system, wherein the signal conditioningbox is configured to turn the control system on and off with a blankingsignal.

EMBODIMENT 105. The method of embodiment 104, wherein turning thecontrol system on and off with the blanking signal respectively enablesand disables a radio frequency amplifier.

EMBODIMENT 106. The method of embodiment 90, wherein the radio frequencytransmit system comprises a transmit coil that is non-planar andoriented to partially surround the region of interest.

EMBODIMENT 107. The method of embodiment 106, wherein the magneticresonance imaging system further comprises a tuning box, wherein thetuning box is configured to alter the frequency response of the transmitcoil.

EMBODIMENT 108. The method of embodiment 90, wherein the gradient coilset is non-planar and oriented to partially surround the region ofinterest, and wherein the gradient coil set is configured to project amagnetic field gradient to the region of interest.

EMBODIMENT 109. The method of embodiment 90, wherein the receive coil isa flexible coil configured to be affixed to an anatomical portion of apatient for imaging within the region of interest.

EMBODIMENT 110. The method of embodiment 90, wherein the receive coil isin one of a single-loop coil configuration, figure-8 coil configuration,or butterfly coil configuration, wherein the receive coil is smallerthan the region of interest.

EMBODIMENT 111. The method of embodiment 106, wherein the transmit coiland the gradient coil set are concentric about the region of interest.

EMBODIMENT 112. A non-transitory computer-readable medium in which aprogram is stored for causing a computer to perform a method forperforming magnetic resonance imaging, the method comprising providingan imaging system comprising a radio frequency receive coil, and apermanent magnet for providing a permanent gradient field. The methodfurther comprises placing the receive coil proximate a target subject;applying a sequence of chirped pulses having a wide bandwidth; applyinga multi-slice excitation along the permanent gradient field, wherein themulti-slice excitation includes exciting multiple slices along an axisof the permanent gradient field, wherein each of the multiple slices hasa bandwidth that is similar to the wide bandwidth of the chirped pulses;applying a phase encoding field along two orthogonal directionsperpendicular to the axis of the permanent gradient field; and acquiringa magnetic resonance image of the target subject.

EMBODIMENT 113. The method of embodiment 112, wherein application of thechirped pulses, multi-slice excitation, and gradient pulses are timed sothat each magnetization refocuses at a time of acquisition of a signal.

EMBODIMENT 114. The method of embodiment 113, wherein each magnetizationfocuses in a region of interest, wherein the region of interestencompasses the target subject.

EMBODIMENT 115. The method of embodiment 114, wherein the region ofinterest has a diameter of 4 to 12 inches.

EMBODIMENT 116. The method of any of embodiments 112 to 115, wherein thechirped pulses comprise identical bandwidths and differing durations.

EMBODIMENT 117. The method of embodiment 116, wherein the chirped pulseshave a bandwidth ranging from 1 kHz to 10 kHz, 10 kHz to 40 kHz, 40 kHzto 100 kHz, 100 kHz to 400 kHz, 400 kHz to 1 MHz, or any ranges ofbandwidth thereof.

EMBODIMENT 118. The method of any of embodiments 112 to 117, wherein thechirped pulses are configured to produce a 1-dimensional signal along anaxis of the permanent gradient field.

EMBODIMENT 119. The method of embodiment 118, further comprisingapplying a plurality of gradient pulses via a gradient coil setorthogonal to the inhomogeneous permanent gradient field, wherein the1-dimensional signal is the first 1-dimensional signal, the gradientpulses are configured to produce a second 1-dimensional signal and athird 1-dimensional signal that are orthogonal to each other and to theaxis of the permanent gradient field.

EMBODIMENT 120. The method of any of embodiments 112 to 119, furthercomprising applying a plurality of gradient pulses via a gradient coilset orthogonal to the inhomogeneous permanent gradient field, whereinthe gradient pulses are configured for encoding spatial information tothe signal.

EMBODIMENT 121. The method of any of embodiments 112 to 120, wherein thecombination of the permanent gradient field and the chirped pulses areconfigured for slice selection in the permanent gradient and a frequencyencoding gradient.

EMBODIMENT 122. The method of any of embodiments 112 to 121, wherein thetarget subject is an anatomical portion of a body.

EMBODIMENT 123. The method of any of embodiments 112 to 122, wherein thereceive coil comprises an array of receive coils and each of the arrayof receive coils is configured for a specific anatomical portion of abody.

EMBODIMENT 124. The method of any of embodiments 112 to 123, wherein thechirped pulses induce a signal in the target subject, and the signal isreceived by the receive coil.

EMBODIMENT 125. The method of any of embodiments 112 to 124, wherein themagnetic resonance imaging system further comprises a signalconditioning box and a control system, wherein the signal conditioningbox is configured to turn the control system on and off with a blankingsignal.

EMBODIMENT 126. The method of embodiment 125, wherein turning the systemon and off with the blanking signal respectively enables and disables aradio frequency amplifier.

EMBODIMENT 127. The method of embodiment 114, wherein the imaging systemfurther comprises a tuning box and a radio frequency transmit coil,wherein the tuning box is configured to alter the frequency response ofthe transmit coil.

EMBODIMENT 128. The method of embodiment 127, wherein the transmit coilis non-planar and oriented to partially surround the region of interest.

EMBODIMENT 129. The method of embodiment 114, wherein the imaging systemfurther comprises a single-sided gradient coil set, wherein the gradientcoil set is non-planar and oriented to partially surround the region ofinterest, and wherein the gradient coil set is configured to project amagnetic field gradient to the region of interest.

EMBODIMENT 130. The method of embodiment 114, wherein the receive coilis a flexible coil configured to be affixed to an anatomical portion ofa patient for imaging within the region of interest.

EMBODIMENT 131. The method of embodiment 114, wherein the receive coilis in one of a single-loop coil configuration, figure-8 coilconfiguration, or butterfly coil configuration, wherein the receive coilis smaller than the region of interest.

EMBODIMENT 132. A non-transitory computer-readable medium in which aprogram is stored for causing a computer to perform a method forperforming magnetic resonance imaging, the method comprising providing apermanent gradient magnetic field; placing a receive coil proximate atarget subject; applying a sequence of chirped pulses having a widebandwidth; selecting a slice selection gradient having the same widebandwidth; applying a multi-slice excitation technique along an axis ofthe permanent gradient magnetic field; applying a plurality of gradientpulses orthogonal to the permanent gradient magnetic field; acquiring asignal of the target subject via the receive coil; and forming amagnetic resonance image of the target subject.

EMBODIMENT 133. The method of embodiment 132, wherein application of thechirped pulses, multi-slice excitation technique, and gradient pulsesare timed so that each magnetization refocuses at a time of acquisitionof the signal.

EMBODIMENT 134. The method of embodiment 133, wherein each magnetizationfocuses in a region of interest, wherein the region of interestencompasses the target subject.

EMBODIMENT 135. The method of embodiment 134, wherein the region ofinterest has a diameter of 4 to 12 inches.

EMBODIMENT 136. The method of any of embodiments 132 to 135, wherein thechirped pulses comprise identical bandwidths and differing durations.

EMBODIMENT 137. The method of embodiment 136, wherein the chirped pulseshave a bandwidth ranging from 1 kHz to 10 kHz, 10 kHz to 40 kHz, 40 kHzto 100 kHz, 100 kHz to 400 kHz, 400 kHz to 1 MHz, or any ranges ofbandwidth thereof.

EMBODIMENT 138. The method of any of embodiments 132 to 137, wherein thechirped pulses are configured to produce a 1-dimensional signal along anaxis of the permanent gradient field.

EMBODIMENT 139. The method of embodiment 138, wherein the 1-dimensionalsignal is the first 1-dimensional signal, the gradient pulses areconfigured to produce a second 1-dimensional signal and a third1-dimensional signal that are orthogonal to each other and to the axisof the permanent gradient field.

EMBODIMENT 140. The method of any of embodiments 132 to 139, wherein thegradient pulses are configured for encoding spatial information to thesignal.

EMBODIMENT 141. The method of any of embodiments 132 to 140, wherein thecombination of the permanent gradient field and the chirped pulses areconfigured for slice selection in the permanent gradient and a frequencyencoding gradient.

EMBODIMENT 142. The method of any of embodiments 132 to 141, wherein thetarget subject is an anatomical portion of a body.

EMBODIMENT 143. The method of any of embodiments 132 to 142, wherein thereceive coil comprises an array of receive coils and each of the arrayof receive coils is configured for specific anatomical portion of abody.

EMBODIMENT 144. The method of any of embodiments 132 to 143, wherein thechirped pulses induce a signal in the target subject, and the signal isreceived by the receive coil.

EMBODIMENT 145. The method of any of embodiments 132 to 144, wherein themagnetic resonance imaging system further comprises a signalconditioning box and a control system, wherein the signal conditioningbox is configured to turn the control system on and off with a blankingsignal.

EMBODIMENT 146. The method of embodiment 145, wherein turning the systemon and off with the blanking signal respectively enables and disables aradio frequency amplifier.

EMBODIMENT 147. The method of embodiment 134, wherein the imaging systemfurther comprises a tuning box and a radio frequency transmit coil,wherein the tuning box is configured to alter frequency response of thetransmit coil.

EMBODIMENT 148. The method of embodiment 147, wherein the transmit coilis non-planar and oriented to partially surround the region of interest.

EMBODIMENT 149. The method of embodiment 134, wherein the imaging systemfurther comprises a single-sided gradient coil set, wherein the gradientcoil set is non-planar and oriented to partially surround the region ofinterest, and wherein the gradient coil set is configured to project amagnetic field gradient to the region of interest.

EMBODIMENT 150. The method of embodiment 134, wherein the receive coilis a flexible coil configured to be affixed to an anatomical portion ofa patient for imaging within the region of interest.

EMBODIMENT 151. The method of embodiment 134, wherein the receive coilis in one of a single-loop coil configuration, figure-8 coilconfiguration, or butterfly coil configuration, wherein the receive coilis smaller than the region of interest.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anyinventions or of what may be claimed, but rather as descriptions offeatures specific to particular implementations of particularinventions. Certain features that are described in this specification inthe context of separate implementations can also be implemented incombination in a single implementation. Conversely, various featuresthat are described in the context of a single implementation can also beimplemented in multiple implementations separately or in any suitablesub-combination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination can in some cases be excisedfrom the combination, and the claimed combination may be directed to asub-combination or variation of a sub-combination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous. Moreover, the separation of various systemcomponents in the implementations described above should not beunderstood as requiring such separation in all implementations, and itshould be understood that the described program components and systemscan generally be integrated together in a single software product orpackaged into multiple software products.

References to “or” may be construed as inclusive so that any termsdescribed using “or” may indicate any of a single, more than one, andall of the described terms. The labels “first,” “second,” “third,” andso forth are not necessarily meant to indicate an ordering and aregenerally used merely to distinguish between like or similar items orelements.

Various modifications to the implementations described in thisdisclosure may be readily apparent to those skilled in the art, and thegeneric principles defined herein may be applied to otherimplementations without departing from the spirit or scope of thisdisclosure. Thus, the claims are not intended to be limited to theimplementations shown herein, but are to be accorded the widest scopeconsistent with this disclosure, the principles and the novel featuresdisclosed herein.

1-111. (canceled)
 112. A magnetic resonance imaging system configured toprovide a permanent gradient magnetic field defining an axis, themagnetic resonance imaging system comprising: a receive coilpositionable adjacent to a target subject; and a control circuitconfigured to: apply a sequence of chirped pulses having a widebandwidth; select a slice selection gradient having the same widebandwidth; apply a multi-slice excitation technique along the axis;apply a plurality of gradient pulses orthogonal to the axis; acquire asignal of the target subject; and form a magnetic resonance image of thetarget subject.
 113. The magnetic resonance imaging system of claim 112,wherein application of the chirped pulses, multi-slice excitationtechnique, and gradient pulses are timed to refocus a magnetization ofthe permanent gradient magnetic field at a time of acquisition of thesignal.
 114. The magnetic resonance imaging system of claim 113, whereineach magnetization is refocused within a region of interest, and whereinthe region of interest encompasses the target subject.
 115. The magneticresonance imaging system of claim 114, wherein the imaging systemfurther comprises a single-sided gradient coil set, wherein thesingle-sided gradient coil set is non-planar and oriented to partiallysurround the region of interest, and wherein the single-sided gradientcoil set is configured to project a magnetic field gradient into theregion of interest.
 116. The magnetic resonance imaging system of claim114, wherein the receive coil comprises a flexible coil configured to beaffixed to an anatomical portion of a patient for imaging within theregion of interest.
 117. The magnetic resonance imaging system of claim114, further comprising a tuning box and a radio frequency transmitcoil, wherein the tuning box is configured to alter the frequencyresponse of the radio frequency transmit coil.
 118. The magneticresonance imaging system of claim 117, wherein the radio frequencytransmit coil is non-planar and oriented to partially surround theregion of interest.
 119. The magnetic resonance imaging system of claim112, wherein the chirped pulses comprise identical bandwidths anddiffering durations.
 120. The magnetic resonance imaging system of claim112, wherein the chirped pulses are configured to produce aone-dimensional signal along the axis of the permanent gradient magneticfield.
 121. The magnetic resonance imaging system of claim 120, whereinthe one-dimensional signal comprises a first one-dimensional signal, andwherein the gradient pulses are further configured to produce a secondone-dimensional signal and a third one-dimensional signal that areorthogonal to each other and to the axis of the permanent gradientmagnetic field.
 122. The magnetic resonance imaging system of claim 112,wherein the gradient pulses are configured for encoding spatialinformation to the signal.
 123. The magnetic resonance imaging system ofclaim 112, wherein the combination of the permanent gradient field andthe chirped pulses are configured for slice selection in the permanentgradient and a frequency encoding gradient.
 124. The magnetic resonanceimaging system of claim 112, wherein the chirped pulses are configuredto induce a signal in the target subject, and wherein the receive coilis configured to receive the signal.
 125. The magnetic resonance imagingsystem of claim 112, further comprising: a signal conditioning box; anda radio frequency transmit system, wherein the radio frequency transmitsystem comprises a radio frequency amplifier and a transmit coil, andwherein the signal conditioning box is configured to enable and disablethe radio frequency amplifier.
 126. A magnetic resonance imaging system,comprising: a radio frequency receive system comprising a radiofrequency receive coil positionable adjacent to a target subject; apermanent magnet configured to provide an inhomogeneous permanentgradient field; a radio frequency transmit system; a single-sidedgradient coil set; and a control circuit communicably coupled to theradio frequency receive system, the radio frequency transmit system, andthe single-sided gradient coil set, wherein the control circuit isconfigured to: apply, by the radio frequency transmit system, a sequenceof chirped pulses; apply a multi-slice excitation pulse along theinhomogeneous permanent gradient field; apply, by the single-sidedgradient coil set, a plurality of gradient pulses orthogonal to theinhomogeneous permanent gradient field; acquire, by the radio frequencyreceive system, a signal of the target subject; and form a magneticresonance image of the target subject.
 127. The magnetic resonanceimaging system of claim 126, further comprising a power source, whereinthe power source is configured to flow current through at least one ofthe radio frequency transmit system and the single-sided gradient coilset to generate an electromagnetic field in a region of interest, andwherein the region of interest is configured to receive the targetsubject.
 128. The magnetic resonance imaging system of claim 126,wherein the multi-slice excitation pulse comprises exciting multipleslices along an axis of the inhomogeneous permanent gradient field. 129.A magnetic resonance imaging system, comprising: a radio frequencyreceive coil configured to be placed adjacent to a target subjectpositioned in a region of interest; a permanent magnet configured toprovide an inhomogeneous permanent gradient field in the region ofinterest; a radio frequency transmit system; and a control circuitcommunicably coupled to the radio frequency receive system and the radiofrequency transmit system, wherein the control circuit is configured to:apply a sequence of chirped pulses having a wide bandwidth; apply amulti-slice excitation along the permanent gradient field, wherein themulti-slice excitation comprises exciting multiple slices along an axisof the permanent gradient field in the region of interest, and whereineach of the multiple slices comprises the wide bandwidth; apply a phaseencoding field along axes perpendicular to the axis of the inhomogeneouspermanent gradient field; and acquire a magnetic resonance image of thetarget subject.
 130. The magnetic resonance imaging system of claim 129,wherein application of the chirped pulses, multi-slice excitation, andgradient pulses are timed to refocus a magnetization of the permanentgradient magnetic field at a time of acquisition of a signal.
 131. Themagnetic resonance imaging system of claim 129, wherein the radiofrequency receive coil is configured to abut an anatomical portion of apatient.